WO2002077399A1

WO2002077399A1 - Building security incorporating lock & latch with electric and/or magnetic pathway across lock.

Info

Publication number: WO2002077399A1
Application number: PCT/NZ2002/000040
Authority: WO
Inventors: David Russell Thompson
Original assignee: David Russell Thompson
Priority date: 2001-03-26
Filing date: 2002-03-26
Publication date: 2002-10-03
Also published as: WO2002077400A2; WO2002077400A3

Abstract

A door latch (1) couples energy between a closed door (3) and its jamb (10), eg for remote control of an on-door lock. The latch includes an energy coupler (20) which is mechanically coupled to the latch bolt. As the bolt advances and retracts across the door-jamb gap, the energy coupler moves similarly. The coupler may couple electromagnetically by a transformer or electrically by contacts (20). A corresponding coupler (31) in an auto-aligning latch strike (12), for co-operating with the latch, is attached to a frame by which the strike is fixed to a door jamb. Movement of the coupler relative to the strike frame is restrained in two of three orthogonal directions, while allowed in the third so that the strike and latch couplers can align. Electrical connection via an elongated and cantilevered electrical contact (25L) in the latch is broken by retraction of the latch bolt, to resist tampering attempts.

Description

Building security incorporating lock & latch with electric and/or magnetic pathway across lock.

This invention relates to security of buildings and enclosures and to latches and locks for doors and other closures for buildings and enclosures.

Particularly, but not exclusively, the invention relates to a combination of a jamb-mounted strike and a door-mounted latch and lock, and the provision of a pathway across the door- jamb interface for the transfer of electrical power for the remote control and/or actuation of the lock.

The invention also relates, in part, to the provision of an electrically conductive pathway between a door and its surrounding jamb.

BACKGROUND TO THE INVENTION

Central locking in motor vehicles and electronic access control in blocks of flats, hotels, and non-domestic buildings are both well known. Although it is possible to use electric strikes, magnetic latches or other devices derived from such access control systems, they do not meet the requirements of central locking systems intended for widespread application in domestic buildings.

A house central locking system requires an electrical supply, a control system that may usually be electrically, electronically, or microprocessor based, cabling to convey electrical energy and signalling for control and status monitoring, actuators to execute commands from the control system, status displays and other interfaces between the control system and the human operator, and interfaces with other systems such as home automation systems or alarm systems.

Most doors are single leaf side hung and most of those are held closed by a tapered latch bolt that may or may not also provide a locking function. A practical house central locking system suitable for widespread domestic application requires a remotely controlled locking device for such a door, and an electrical connection between the door locking device and the central control system for the purposes of actuating the lock and conveying door and/or lock status or other information, eg activation of a doorbell.

Preferably, electrically operated door hardware suitable for such a domestic central locking system should not detract from the architecture or decor of the home. For example, a plethora of hardware on a door is not a good look.

Suitable door hardware should preferably fit within the spaces available in the stile and in the jamb as currently used by industry standard door hardware. Removing too much material from either door or j amb may result in reduced strength and hence reduced ability of the door to withstand forced entry. Preferably, an electrically operated lock and its electrical connections should be compatible with existing design standards and dimensions and not require specially engineered or modified doors and jambs.

In the most common door latching and locking arrangement, a manual latching and locking mechanism is located on the door itself which facilitates one-handed unlatching and opening ofthe door. The latching mechanism is driven by a doorknob, handle or turn, or a key when the latch is incorporated with the locking mechanism.

Preferably, a domestic electrically-operated door lock should also be located on the door itself to conform to widely accepted existing styles and practices. Architectural details can make it difficult for a lock to be mounted off the door because ofthe limited space available in the jamb to accommodate such a mechanism.

Electrically operated locks must be operable even if the central locking system has failed, due for example to failure or disconnection ofthe power supply. It is desirable, especially in such a power failure situation, that an electrically operated lock can be locally operated, for example by a mechanical key-operated mechanism such as are widely known. This would be preferable to a reliance on back-up power supplies.

Electric lock actuation should co-operate with the alternative, eg mechanical, actuation system to lock and unlock the door. It is not acceptable for one locking means to have been set to its locking state and for the door to then remain unlocked because the door has not also been locked by the alternative means. Currently used arrangements, for example where a manually locally operated lock bolt co-operates with a remotely-controlled electrically-operated strike, fail in this respect, hi this example the door will only be locked if both the strike and the bolt are set in their respective lock states.

International Patent Application WO 00/77330 describes a door-mounted on-line lock, controllable from a central station via a power coupling between the door and frame. The coupling provides a path for power and data transmission when the door is closed. Both transformer couplers and electrical contact couplers are described.

SUMMARY OF THE INVENTION

It is an object of an embodiment ofthe present invention to provide a latch device by which energy may be coupled between a door and a surrounding door jamb when the door is closed in the jamb, or to at least provide the public with a useful choice.

Accordingly, in a first aspect the invention may broadly be said to consist in a latch means including a support and a latch bolt, the latch bolt being moveable relative to the support, between a protruded position in which a portion ofthe latch bolt protrudes from the support and a retracted position in which the portion of the latch bolt is substantially retracted behind the support, characterised in that the latch means also includes at least one energy coupler, the or each energy coupler being moveable relative to the support between an extended position in which a portion of the coupler extends from the support and a withdrawn position in which the portion ofthe coupler is substantially withdrawn behind the support, the or each coupler being mechanically associated with the latch bolt so that the or each coupler is moved from the withdrawn position toward the extended position by movement ofthe latch bolt from the retracted position toward the protruded position and the or each coupler is moved away from the extended position to the withdrawn position by movement ofthe latch bolt from the protruded position to the retracted position.

Preferably the latch bolt is moveable substantially rectilinearly between the protruded position and the retracted position.

Preferably the latch means includes an energy coupler which is an electromagnetic coupler. Preferably the electromagenetic coupler is a half transformer having a core and a winding.

Preferably the latch bolt is the electromagenetic coupler.

Preferably the half transformer is mechanically attached to the latch bolt but moveable relative to the latch bolt.

Alternatively the or each energy coupler is an electrical conductor.

Preferably at least one ofthe electrical conductors is attached to, but electrically insulated from, the latch bolt.

Preferably the portion ofthe latch bolt has a bevelled face for co-operating in use with a strike, and at least one ofthe electrical conductors is fixed to the latch bolt and exposed on the bevelled face.

Preferably the portion ofthe latch bolt has a bevelled face for co-operating in use with a strike, the portion ofthe latch bolt has a non-bevelled face opposite the bevelled face, and at least one ofthe electrical conductors is fixed to the latch bolt and exposed on the non- bevelled face.

Preferably at least one ofthe electrical conductors is resiliently mounted on the latch bolt and resiliently biased toward the extended position.

Preferably at least one of the electrical conductors makes electrical connection with a respective electrical contact mounted to the support, the connection being made at least when the energy coupler is substantially at the extended position.

Preferably each of said electrical conductors making electrical connection makes electrical connection with the respective electrical contact at least when the energy coupler is at any position between the extended position and an intermediate position being part way between the extended position and the withdrawn position. Preferably each of said electrical conductors making electrical connection makes electrical connection with the respective electrical contact when the energy coupler is at any position between and including the extended position and the withdrawn position.

Preferably each of said electrical conductors making electrical connection at least when the energy coupler is substantially at the extended position, does not make electrical connection with the respective electrical contact when the energy coupler is not substantially in the extended position.

Preferably each electrical contact is elongated and is insulated over a portion of its length and the respective electrical conductor physically contacts the insulated portion and does not make electrical connection with the contact when the respective energy coupler is not substantially in the extended position.

Preferably the latch means is fitted to a door surrounded by a door jamb, and at least one ofthe energy couplers forms part of a circuit by which energy can flow between the latch means and the jamb, when the door is latched in the jamb.

Preferably the support carries a locking means and a lock-unlock actuator by which the locking means may be actuated to change between a locked configuration and an unlocked configuration, and the lock-unlock actuator can be powered to actuate the locking means by energy flowing between the jamb and the lock-unlock actuator, when the door is latched in the jamb.

Preferably the latch means is fitted to a door, and the door is also fitted with a locking means that is distinct from the latch means, the locking means having a lock-unlock actuator by which the locking means may be actuated to change between a locked configuration and an unlocked configuration, and the lock-unlock actuator can be powered to actuate the locking means by energy flowing between the jamb and the lock-unlock actuator via the latch means, when the door is latched in the jamb.

Preferably the latch bolt is one ofthe electrical conductors. In a second aspect the invention may broadly be said to consist in a strike means for use with a co-operating latch means, the strike means having a strike plate, characterised in that the strike means is for co-operating with a latch means having at least one electrical conductor, and the strike means has at least one electrical contact located for respective electrically-contacting engagement by the at least one electrical conductor of the cooperating latch means.

Preferably the strike means includes a contact carrier and the at least one electrical contact is resiliently mounted on the contact carrier.

Preferably the contact carrier includes a pivot pin and the at least one electrical contact is mounted for resilient rotation about the pivot pin.

Preferably the contact carrier is movable relative to the strike plate and the contact carrier includes a bevelled surface against which in use a latch bolt ofthe co-operating latch means can act to move the contact carrier relative to the strike plate to reduce misalignment between the latch bolt and the contact carrier.

In a third aspect the invention may broadly be said to consist in a contact pair including first and second electrical contacts, the first contact being moveable relative to the second contact in a substantially rectilinear direction from a first relative position to a second relative position, and the contacts being in mutual electrical connection at least when the first contact is substantially at the first relative position, wherein the second electrical contact is elongated and cantilevered from an attachment point at one of its ends.

Preferably the contacts are in mutual electrical connection when the first contact is at any relative position between the first relative position and an intermediate relative position being part way between the first and second relative positions.

Preferably the second contact is electrically insulated over a portion of its length and the first contact physically contacts the insulated portion and does not make electrical connection with the second contact, when the first contact is substantially at any relative position between the intermediate relative position and the second relative position. Alternatively the contacts are in mutual electrical connection when the first contact is at any relative position between and including the first and second relative positions.

Preferably the contacts are not in mutual electrical connection when the first contact is not substantially at the first relative position.

Preferably the second contact is electrically insulated over a portion of its length and the first contact physically contacts the insulated portion and does not make electrical connection with the second contact, when the first contact is not substantially at the first relative position.

In a fourth aspect the invention may broadly be said to consist in a latch strike having a frame by which the strike may be attached to a door jamb, and a carrier for carrying a part of at least one energy coupling pathway, the carrier being attached to the frame by an attachment means, wherein movement ofthe carrier relative to the frame in two of three orthogonal directions is restrained while being allowed in the third orthogonal direction.

Preferably the carrier is U-shaped with two limbs extending from a portion linking the proximal ends ofthe two limbs, and attachment ofthe carrier to the frame is by way ofthe linking portion.

Preferably the distance between the inside faces of the limbs of the U-shaped carrier increases toward the distal ends ofthe limbs.

Preferably the carrier is moveable in the third orthogonal direction in response to an externally applied force and, in the absence of an externally applied force, the carrier is retained by the attachment means in a fixed position relative to the frame.

Preferably the frame has one or more slots oriented in the third orthogonal direction and the attachment means is at least two fasteners which are slidingly fitted in at least one ofthe slots.

Preferably the carrier supports at least one electrical contact, the contact being electrically insulated from the carrier and frame. The invention may also broadly be said to consist in any alternative combination of parts or features which are mentioned in the specification or shown in the accompanying drawings. Equivalents of these parts or features which are not expressly indicated are nevertheless deemed to be included.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments ofthe invention will be described, by way of example only, with reference to the accompanying drawings in which: Figures 1 A and IB show plan and side elevation cross-sectional views of portions of a door and jamb fitted respectively with an electrically-contacting mortise latch and strike,

Figure 1C shows plan and side elevation views of an alternative latch bolt for use in a mortise latch ofthe type shown in Figures 1A and IB,

Figure 2 shows, in plan view, an internal sliding latch contact in a configuration corresponding to a retracted latch bolt,

Figure 3A shows, in plan view, an alternative internal sliding latch contact in a configuration corresponding to an extended latch bolt,

Figure 3B shows, in plan view, the alternative sliding latch contact of Figure 3 A in a configuration conesponding to a retracted latch bolt, Figure 4A shows a plan view of a contact,

Figure 4B shows an end elevation view ofthe contact shown in Figure 4 A,

Figure 5 A shows a plan view, partly in cross-section, of an alternative electrically- contacting tubular latch, with parts broken away to show inner details,

Figure 5B shows a side elevation view, partly in cross-section, of the alternative electrically-contacting tubular latch of Figure 5 A,

Figure 6 A shows a side elevation of a cross section at line D-D' of an auto-aligning contact carrier shown in Figure 6B, in co-operation with a latch bolt ofthe type seen in the mortise latch of Figure 1,

Figure 6B shows an end elevation as seen in direction C ofthe auto-aligning contact carrier of Figure 6 A,

Figures 7A and 7B show plan and side elevation cross-sectional views of portions of a door and jamb fitted respectively with an alternative electrically-contacting mortise latch and strike, Figure 8 shows a diagrammatic partial cross-sectional plan view of parts of another latch bolt and an associated strike,

Figure 9 shows a diagrammatic partial cross-sectional side elevation of parts of yet another latch bolt and an associated strike, Figures 10A, 10B and IOC and 11 A, 1 IB and 11C show diagrammatic partial cross- sectional plan views of parts of a rotating end entry latch bolt and an associated strike, showing phases of coupling and decoupling actions,

Figure 12 shows a perspective view of a side entry latch bolt,

Figures 13A, 13B and 13C show diagrammatic partial cross-sectional plan views of parts ofthe side entry latch bolt of Figure 12 and an associated strike, showing phases of a coupling action,

Figures 14A, 14B and 14C show diagrammatic partial cross-sectional plan views of parts of a first type of end entry latch bolt and an associated strike, showing phases of a coupling action, Figure 15 shows a perspective view of a second type of end entry latch bolt,

Figures 16A, 16B and 16C show diagrammatic partial cross-sectional plan views of parts of the second type of end entry latch bolt of Figure 15 and an associated strike, showing phases of a coupling action,

Figure 17 shows a perspective view of a third type of end entry latch bolt, and an associated strike contact assembly,

Figure 18 shows an end elevation view of a strike with a rotating contact assembly for use with the end entry latch device of Figure 19, and as seen in Figures 20A, 20B and 20C,

Figure 19 shows an end elevation view of an end entry latch device, for use with the strike of Figure 18, and as seen in Figures 20A, 20B and 20C,

Figures 20A, 20B and 20C show partial cross-sectional plan views ofthe end entry latch device, as shown in Figure 19, and an associated strike, as shown in Figure 18, showing aspects of a coupling action,

Figures 21 A and 21B show perspective views of a latch and strike using magnetic coupling for transfer of energy between a door and jamb,

Figures 22A and 22B show partial cross-sectional side views of an alternative latch and strike using magnetic coupling for transfer of energy between a door and jamb, showing phases of a coupling action, Figures 23 A and 23B show partial cross-sectional plan view ofthe alternative latch and strike of Figures 22A and 22B, as seen looking upward from below, showing phases of a coupling action,

References above to plan views, eg Figure 1 A, may be best understood as looking vertically downward at the latch or strike when fitted to a single leaf side hung door or jamb. The side elevation views referred to above, of either strike or latch devices, eg Figure IB, are horizontal views as seen in the direction when looking substantially perpendicularly at the major face ofthe door when closed in the jamb. References above to an end elevation view of a strike, eg Figures 6B and 18, may be best understood as looking at the exposed face of the strike when fitted in a jamb, and to an end elevation view of a latch device, eg Figure 19, as looking at the exposed forend or face plate ofthe latch device when fitted in a door.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the figures it will be appreciated that the invention can be implemented in many forms for a wide variety of users without departing from the scope ofthe claims. Preferred forms are given here by way of example only.

Like features appearing in the Figures are generally labelled with like labels. Descriptions of features given in respect of one Figure are to be understood as applying, where not inappropriate, to like features with like labels appearing in other Figures.

Figure 1 A is a plan view ofthe cross-section at line A-A' of Figure IB, and Figure IB is a side elevation view ofthe cross-section at line B-B' of Figure 1A.

In Figures 1 A and IB a mortise latch 1 is mounted in a cutout or mortise 2 in the stile of a door 3. The latch includes a latch bolt 4 with a bevelled or tapered portion 5 which is located in an aperture in a forend or latch face plate 6 which is rebated in the door to present an external surface substantially flush with the surrounding surface ofthe door.

The latch bolt is carried by a latch bolt carrier 7. The carrier and the latch bolt are biassed, by a spring (not shown), toward an extended or protruding configuration, shown in Figures 1A and IB, in which the distal tapered end ofthe latch bolt protrudes beyond the face plate 6.

The door is side hung and is mounted in a surrounding jamb 10. When the door 3 closes in the jamb 10, the bevelled face 11 of the tapered portion of the latch bolt engages a strike 12. The previously protruding portion ofthe latch bolt momentarily retracts into the latch housing (not shown). When the door is substantially in its closed position and latch bolt is aligned with an aperture 13 in the strike, the latch bolt is urged towards its extended or protruding configuration by the biassing spring and the door is latched closed by interaction between the non-bevelled face 14 ofthe tapered portion ofthe latch bolt and an edge 15 ofthe aperture in the strike. This latching action is well-known and widely used.

The latch bolt carries electrically conductive contact strips 20 on the bevelled face ofthe tapered portion ofthe latch bolt. The contact strips are mounted in a rebate in the bevelled face so that they present an external surface that is substantially flush with the surrounding bevelled face ofthe latch bolt.

The latch bolt is made from brass, although other suitable metals or materials can be used. The contact strips are electrically isolated from the latch bolt material by being embedded in, or adhered to, an electrically insulating material 22, as best seen in Figure IB.

Figure 1C shows plan and side elevation views of one alternative for the latch bolt 4 in mortise latches ofthe type shown in Figures 1A and IB. Instead ofthe latch bolt having attached or embedded contact strips as shown in Figures 1 A and IB, the latch bolt itself provides the latch contacts in the latch bolt of Figure lC.

The latch bolt body is divided, preferably longitudinally, into multiple segments or portions that are electrically insulated from one another, such as by insulated separators, and from other surrounding electrically conductive material in the latch. This may be achieved by manufacturing the latch housing from an electrically non-conductive material. Some segments may be used to provide electrically conductive paths across the door-jamb gap while others may be used to provide a mechanical and/or electrical shield against attempts to tamper with, or defeat, a lock associated with the latch. In Figure 1C, the latch is split longitudinally into three segments; an upper segment 450, a lower segment 452, and a shield segment 453. The upper and lower segments are attached to respective sides of a first layer 454 of electrically insulating material. The upper and lower segments are also both attached to one side of a second layer 456 of electrically insulating material. The shield segment 453 is attached to the other side of the second layer 456. The upper and lower segments present, at bevelled face 458, respective contact surfaces 460, 462 for engaging corresponding complementary contacts in a strike with which the latch bolt co-operates. Such complementary contacts are not shown in Figure 1C but could be contacts such as the carrier-mounted strike contacts 31 shown in Figures 1 A and IB and further described below.

The shield arrangement shown in Figure 1C is particularly suitable for use in an outwardly opening door. In this case, the shield segment 453 shields the upper and lower contact segments 450, 452 and prevents easy access to the contact segments from the exterior of the outwardly opening door. This shielding reduces the likelihood of a successful tampering attempt, for example the unauthorised application of an unlock actuation voltage via the latch bolt contact segments 450, 452.

The shield segment 453 acts as a mechanical barrier by being interposed between the contact segments 450, 452 and the external side ofthe outwardly opening door. The shield segment is also electrically isolated from the contact segments, so that application of voltage to the shield segment has no effect on the contact segments and any lock bolt actuation circuit associated with the contact segments.

In the arrangements shown in Figures 1 A and IB, each contact strip 20 extends from an outer end at a position at or near the tapered tip 23 of the latch bolt to an inner end at a position which remains behind the latch face plate 6 and inside the latch housing, not shown, even when the latch bolt is in the extended or protruding configuration.

The continuation ofthe conducting paths from the contact strips could be accomplished by using a flexible metallic wire or braid, but the small spaces available if keeping within industry standard latch dimensions and the comparatively long travel ofthe latch bolt mean that eventual, if not early, failure due to excessive flexing ofthe wire or braid is difficult to avoid. Sliding connections as described below and shown in some detail in Figures 2, 3A, 3B, 4A and 4B are used in preference to flexible connections.

The contact strips each have, at their inner ends, a raised contact 24 which slidingly engages a respective spring steel wire contact 25U, 25L. Each spring wire contact is attached at one end by a fastener 26 to a fixed part 27 ofthe latch. The fastener insulates the spring wire contact from the fixed part ofthe latch housing.

The spring wire contacts are each covered with an electrically insulating sheath or sleeve 28 over a part of their length, leaving at least the end of the spring wire opposite the attachment end uninsulated. When the latch bolt is substantially in the protruding configuration the raised contacts 24 electrically contact the uninsulated ends of respective spring wire contacts. As the latch bolt retracts, each raised contact slides along a respective spring wire contact, remaining physically in contact with the spring wire or its insulating sleeve. Electrical contact between the contact strip and its respective spring wire contact, via the raised contact, is broken when the raised contact reaches the insulating sleeve.

Figure IB illustrates two options ofthe placement ofthe insulating sleeve 28 on the spring wire contacts 25. The insulating sleeve 28 on the upper spring wire contact 25U as shown in Figure IB (and also seen in plan view in Figure 2), extends only about halfway from the attachment end ofthe spring wire contact. The distal end ofthe upper spring wire contact has an uninsulated end portion 25' with an enlarged diameter which substantially matches the diameter ofthe insulation covering the insulated portion. The end portion 25' is made from brass or copper and is eccentric to the spring wire to which it is conductively attached, such as by brazing or soldering.

As shown in Figure IB, and in plan view in Figures 3 A and 3B, the insulating sleeve 28 on the lower spring wire contact 25L extends along most ofthe length ofthe contact, leaving only an enlarged end tip 29 uninsulated for contact by the raised contact 24 on the contact strip 20 only when the latch bolt is substantially at the protruding configuration, for example within about the last 0.5 to 1 mm of latch bolt travel. The enlarged end tip is made from brass or copper and is eccentric to the spring wire to which it is conductively attached, such as by brazing or soldering. The provision of insulation along most ofthe length ofthe lower spring wire contact 25L (so that electrical contact between it and the contact strip 20 is broken after only about 0.5 to 1 mm of travel ofthe latch bolt 4 from its extended position) is a security measure which increases the difficulty of making unauthorised attempts to apply voltage to the contact strips such as when trying to activate a lock to which the latch contacts are connected. For example, if the latch is even slightly retracted, eg by 0.5 to 1.0 mm, such as during the insertion of electrically energised conductors into the gap between the door and strike in an attempt to apply an 'unlock' voltage, the connection between the latch bolt contacts and the lock actuator will be broken, preventing application of an actuating voltage to the lock bolt actuator to unlock the door. An enhancement of this security measure is discussed below.

Figures 2, 3 A, 3B, 4A and 4B show only a portion 20' ofthe latch bolt contact strip 20 seen in Figures 1 A and IB.

In Figure 2 the sliding contact 24 is shown in the 'latch bolt retracted' position and is in electrical contact with the enlarged diameter portion 25' ofthe spring wire 25U.

h Figure 3A the sliding contact 24 is shown in the 'latch bolt extended' position and is in electrical contact with the enlarged end tip 29 ofthe spring wire 25L.

In Figure 3B the sliding contact 24 is shown in the 'latch bolt retracted' position and is in physical contact with the insulated sleeve 28, but is not in electrical contact with the spring wire contact 25L.

The spring wire contacts 25U, 25L are brazed or otherwise conductively fixed to fasteners 26. The fasteners attach the spring wire contacts to the fixed part 27 ofthe latch in association with electrical insulators 16, seen best in Figures 2, 3 A and 3B, to provide electrical isolation between the spring wire contacts and the fixed part 27 ofthe latch.

The fasteners are also associated with connection terminals 17 by which the spring wire contacts may be connected to other circuit elements, eg a lock bolt actuator, in an associated but separate lock or in the latch itself when integrated with a lock. Figures 4A and 4B are plan and end elevation views, respectively, showing further detail ofthe sliding contact 24 which has a cylindrical cutout 18 which is shaped to conform to the spring wire contact along which it slides. The cutout 18 has a ramp 18' at one end which engages a sloping surface 19 (seen in Figure 3B) on the enlarged end tip 29 ofthe spring wire contact.

The ramp and sloping surfaces facilitate the riding up of the enlarged tip on the sliding contact, against the spring bias inherent in the spring wire contact. This provides a desirable increase in contact pressure and a mutual wiping action ofthe contacting surfaces. Both actions help to keep the contact surfaces clean and free of contaminants or other interferences that could compromise the integrity ofthe electrical connection between the contacts.

In Figures 1A and IB, the strike 12 is mounted in the door jamb 10 and includes contacts 31 mounted on a carrier 32 which rotates on a vertical pivot shaft 33 against the bias provided by spring 34. The strike contacts 31 are generally housed within the recess or cutout 35 conventionally provided in the door jamb behind the front plate ofthe strike 12 to accept the protruding tapered end ofthe latch bolt. Some enlargement ofthe recess may be necessary to accommodate the strike contact anangement.

Flexible leads 36 connect the strike contacts to further circuit connections (not shown), such as power supply lines to a remote source of power for actuating a lock bolt actuator.

The contact strips on the bevelled face ofthe latch bolt are wider than the strike contacts to allow for a lack of precision in the vertical alignment between the latch and the strike.

The strike contacts are biassed by the spring 34 out toward the aperture 13 in the strike plate. When the door is closed the latch bolt engages the strike and momentarily retracts before extending to protrude into the strike recess whereupon the contact strips on the bevelled face ofthe latch bolt engage the strike contacts. The strength ofthe strike contact carrier spring 34 is less than that ofthe latch bolt biassing spring so that, although the strike contacts engage and electrically connect with the latch contact strips, the extension ofthe latch, and therefore the door latching action, is not impeded. The geometry ofthe strike contact arrangement is such that when the latch bolt 4 engages the strike contacts 31, the point of first contact is such that there is a net force that is clockwise (as seen in the Figure 1 A) on the contact carrier 32 about the pivot shaft 33. This force moves the contacts away from the path of the latch bolt, allowing substantially unimpeded entry ofthe latch bolt into the strike recess.

The electrical contacts and strips in the latch and strike are made from brass or copper but other conductive materials could be used, and may be necessary, for example in corrosive or contaminating environments.

In an alternative strike contact arrangement, not shown, the rotatable contact carrier 32, spindle or pivot shaft 33 and spring 34 as described in relation to Figures 1 A and IB are dispensed with and strike contacts are simply provided as resilient contacts, rigidly fixed at one end to the strike or an intermediate carrier and suitably shaped and positioned to engage the latch bolt contacts when the door is latched closed. The resilient contacts flex when engaging the latch bolt contacts and may be made from a suitable material such as spring brass or brass coated spring steel.

The mortise latch bolt and latch strike shown in Figures 1 A and IB may be used to provide a connection between the jamb and the door for remotely controlling and/or actuating a door lock and monitoring the status ofthe door and lock.

The security measure discussed above (in relation to the breaking of the connection between at least one of the latch contact strips 20 and a lock bolt actuator to thwart an unauthorised attempt to apply an unlocking voltage to the actuator) can be enhanced by applying a short circuit across the strike contacts 31 when there is no authorised application of an 'unlocking' or 'locking' voltage. If the latch bolt 4 is retracted, even slightly such as by 0.5 to 1.0 mm, in an unauthorised attempt to remove the short circuit from across the latch contact strips 20, the connection between the latch contact strips and the lock actuator will be broken, preventing unauthorised application of an 'unlock' voltage to the lock actuator. The break of the connection between the latch contact strips 20 and the lock actuator is provided by the sliding movement of the raised contact 24 from electrical contact with the end tip 29 to physical contact with the insulating sleeve 28 around the spring steel wire contact 25L. The short circuit across the strike contacts 31 is maintained across the latch contact strips 20 at least until the connection between the latch contact strips 20 and the lock actuator is broken. This is ensured by the spring loaded rotation of the latch contact carrier 32 which rotates the strike contacts 31 anti-clockwise, as seen in Figure 1A, to maintain the strike contacts against the latch contact strips 20 as the latch bolt 4 retracts, at least until the connection between the latch contact strips 20 and the lock actuator is broken.

Tamper resistance may also be enhanced by use of a pawl or stop, either electrically or mechanically actuated, to engage and prevent the latch bolt from being withdrawn at least when the door is locked. This prevents unauthorised access to the latch bolt contacts that might otherwise enable the lock to be defeated by electrical activation of the lock by application of a voltage across the latch bolt contacts. In a variation, instead of lock activation actuating a pawl or stop to prevent withdrawal ofthe latch bolt, lock activation causes the door handle to be disengaged from the latch bolt. The prevention of withdrawal ofthe latch bolt by the pawl or stop, or by disengagement ofthe door handle, may provide the locking function in addition to or instead of an independent lock bolt.

Figures 5 A and 5B show a portion of a so-called 'tubular' latch 40. The latch includes a latch bolt 44 with a bevelled or tapered portion 45 wliich is located in an aperture in a latch forend or face plate 46 which is rebated in a door, not shown, to present an external surface substantially flush with the surrounding surface ofthe door.

The latch bolt is carried in a latch tube 47. The latch bolt is biassed by a pair of springs (only one spring 48 being seen Figures 5A and 5B) toward an extended or protruding configuration, shown in Figures 5 A and 5B, in which the bevelled portion 45 ofthe latch bolt protrudes beyond the face plate 46.

When the door in which the tubular latch is fitted closes, the latch bolt operates with a momentary sequential retraction and re-extension action similar to that already described above in relation to the mortise latch.

The latch bolt operates with a deadlocking function controlled by deadlocking pin 49, seen in Figure 5 A, in a known manner. The latch bolt 44 carries brass contact strips 50 on the bevelled face 51 of the tapered portion ofthe latch bolt. The contact strips are mounted in a rebate 52 in the bevelled face so that they present an external surface that is substantially flush with the surrounding bevelled face ofthe latch bolt.

The latch bolt is made from brass, although other suitable metals or materials can be used. The contact strips are electrically insulated from the latch bolt material by being embedded in, or adhered to, an electrically insulating material 53. The outer end of each contact strip is secured to the latch bolt by a respective reverse tapered stud 54 embedded in the insulating material 53 which fills a cavity 55 near the tip ofthe latch bolt.

The inner ends ofthe contact strips 50 are brazed 50' to the outer end of respective spring steel wire contacts 56U, 56L which are embedded in channels 57 in the latch bolt by the insulating material 53. The spring wire contacts are carried by a common support plate 58 which is brazed to the back of the latch bolt. Insulators 59 maintain electrical isolation between the spring wire contacts and the support plate.

The latch tube has an opening 60 through which the support plate extends.

The spring wire contacts 56U, 56L are cantilevered from the support plate to slidingly contact fixed contacts 61U, 61L which are attached to the latch tube 47. The fixed contacts 61U, 61L are insulated from the latch tube by insulators 62, seen in Figure 5 A.

Figure 5B shows the tubular latch as having an insulating sleeve 63 on the upper spring wire contact 56U. The lower spring wire contact 56L has no insulating sleeve but has an uninsulated end portion 64 with a diameter larger than that ofthe spring wire. The end portion 64 is conductively attached, such as by brazing to the spring wire contact 56L.

As shown in Figure 5B, the insulating sleeve 63 on the upper spring wire contact 56U extends along most of the length of the contact, leaving only an enlarged end tip 65 uninsulated for contact by the upper fixed contact 61U only when the latch bolt is substantially at the protruding configuration, for example within about the last 0.5 to 1 mm of latch bolt travel. The enlarged end tip 65 is eccentric to the spring wire to which it is conductively attached, such as by brazing. When the latch bolt is substantially at its full extension, the respective fixed contacts 61U, 61L electrically contact the uninsulated end portion 64 ofthe lower spring wire contact 56L and the enlarged tip 65 ofthe upper spring wire contact 56U.

As the latch bolt retracts, the upper wire contact 56U slides along over the upper fixed contact 61U, the latter remaining physically in contact with the insulating sleeve 63. Electrical contact between the upper one ofthe contact strips 50 and its associated upper fixed contact 61L, via the sliding spring wire contact 56U, is broken when the insulating sleeve 63 reaches the fixed contact. This occurs within about 0.5 to 1 mm of latch travel from the fully extended position.

Electrical contact between the lower one ofthe contact strips 50 and its associated lower fixed contact 61L, via the uninsulated end portion 64, is maintained as the latch bolt retracts.

The tubular latch bolt is used in association with a latch strike, as disclosed above in relation to the mortise latch, to provide a connection between jamb and door for remotely controlling and/or actuating a door lock and monitoring the status ofthe door and lock.

It is noted that in some commonly used tubular latch bolts, the bevelled front face ofthe latch bolt is provided with a curve in the vertical direction. This curvature helps to ensure that contact between the strike plate and the latch bolt is made approximately midway between the upper and lower edges ofthe bevelled surface, rather than at either of those edges as would otherwise occur in practice when the latch bolt and strike are not perfectly aligned. The curvature of the bevelled face ofthe latch bolt helps to reduce some ofthe moment forces acting on the latch bolt when contacting the strike by reducing off-centre forces.

However, the latch bolt 44 shown in the tubular latch of Figures 5 A and 5B has a surface on the bevelled portion 45 that is substantially flat in the vertical direction. This absence of vertical curvature on the face of the bevelled portion helps to ensure that the physical contact between the latch bolt and the strike plate is predominantly at either the upper or lower edge. The contact strips 50 are fitted vertically mid way between the upper and lower edges ofthe bevelled face 51 where they will not be exposed to the normal wear and tear associated with the engagement ofthe latch bolt and strike. Any slight misalignment between latch and strike, which generally occurs in most practical latch installations, will cause either the top or bottom edge ofthe bevelled face 51 ofthe latch bolt 44 to contact the strike and take most ofthe wear.

In the latch arrangement ofthe embodiments shown in the figures, the latch bolt contacts are located on the bevelled side face of the latch bolt. Other latch bolt locations (not shown) are envisaged. For example, one contact strip insulated from the latch bolt and mounted as shown above on the bevelled face ofthe latch bolt could be used in conjunction with the metallic latch bolt itself as the other contact. In another arrangement the latch bolt contacts are located on the upper and/or lower surfaces ofthe latch bolt.

In yet another such arrangement the latch bolt contacts are located on the flat side face of the latch bolt opposite the bevelled face; ie the latch bolt surface which engages the edge ofthe aperture in the front plate ofthe strike when latching the door in its closed position.

This latter arrangement is particularly advantageous when used on an inward opening door as it places the latch bolt contacts on the back face ofthe latch bolt, facing away from the front or outside face ofthe door. This increases the difficulty of making contact with latch bolt contacts from outside the closed door, such as during an unauthorised attempt to operate the lock by applying a voltage to the latch bolt contacts. Contacts mounted on the back face ofthe latch bolt could be slightly recessed into the face ofthe bolt to avoid being electrically shorted by engagement with the edge ofthe front plate ofthe strike.

The strike contact carrier can be designed to control door rattle, for example by being adjustable or spring loaded to act against the latch bolt and urge the door towards the edge ofthe rebate in the door frame. Door rattle can arise when a door that is closed and latched in a door frame can move relatively freely between a first position in which the front face ofthe closing door abuts a face ofthe rebate in the frame and a second position in which the flat (rear) side of the latch bolt engages a corresponding edge of the aperture in the strike plate. Although this door movement is usually over only a very small distance, it nevertheless can allow a door that is latched closed to rattle, for example under the influence of variations in air pressures on respective sides ofthe closed door. If a door that otherwise would have some degree of freedom of movement, as described above, is held against the rebate by the strike contact carrier acting against the flat side face ofthe latch bolt, the tendency ofthe door to rattle can be reduced.

It is preferable that door rattle be controlled by biassing the door against the door frame rebate by a sideways pressure applied via the latch bolt rather than the lock bolt, where these are provided as distinct elements. There are two reasons for this preference. Firstly, any reduction in a tendency for door rattle is achieved whenever the door is latched closed ie regardless of whether the door is also locked. Secondly, if the lock bolt is to be extended and retracted electrically, or by other non-manual means, the force available may be limited so the lock bolt should be an easy fit in the strike and not encounter any restrictions or impediments to full extension to a locked position.

It is to be understood that in the alternative arrangements discussed above, where latch bolt contacts are not located on the bevelled face of the latch bolt, the contacts in a strike associated with the latch are located in corresponding positions to provide electrical circuits between door and frame when a door on which the latch is fitted is closed in a frame in which the strike is fitted.

Figures 6 A and 6B show a latch strike 70 for fitting to a door jamb. The latch strike has a generally U-shaped contact carrier 71 wliich provides automatic vertical alignment of strike contacts carried by the carrier (but not shown), with contact strips 20 on a latch bolt 4' of a latch (not shown) fitted to an associated door hung in the jamb.

The strike contacts (not shown) are mounted in, but electrically insulated from, the carrier

71 which is attached by two fasteners 72 to a rear plate 73 ofthe strike in a manner which allows for relative vertical movement. The carrier is spaced from the rear plate by washers 74. The fasteners are fitted in vertically oriented slots 76 in the rear strike plate so that the carrier plate is able to move vertically. The carrier is drawn toward the rear strike plate by springs 75 fitted to the fasteners to provide a frictional resistance against movement ofthe carrier relative to the strike.

The carrier 71 bears against the rear strike plate 73 via the intermediate spacing washers 74 to resist horizontal movement of the carrier in direction of arrow C. Because the fasteners 72 are fitted in vertical slots 76, movement of the carrier 71 in a horizontal direction perpendicular to arrow C is also resisted.

The U-shaped carrier 71 has upper and lower arms 82 which extend toward an opening 77 in the front strike plate 78. If there is a vertical misalignment between the strike contact carrier 71 and the latch bolt 4' of a co-operating door latch, the carrier arms 82 are engaged by the upper and lower surfaces 79 ofthe latch bolt 4'.

The outer ends ofthe arms 82 are flared 80 to co-operate with bevelled corners 81 on the latch bolt to guide the arms 82 ofthe strike contact carrier 71 into sliding engagement with the latch bolt. This provides a vertically oriented realignment force on the contact carrier, which overcomes the frictional resistance provided by springs 75 and realigns the contact carrier with the latch bolt if a misalignment has occurred since the door was last closed and latched. The contact carrier and its mounting plate is made sufficiently rigid so that realignment rather than just flexure, eg ofthe arms, occurs.

It appears that in practice, when a door is shut and the latch bolt 4' jumps into the strike recess, the bevelled comers 81 of the latch bolt impact on the contact carrier 71 which moves and overshoots slightly so that there is no contact between the latch bolt and the contact carrier until a further misalignment between the latch bolt and the contact carrier.

The size of the flare 80 of the arms 82 and the bevelled corners 81 on the latch bolt are small because automatic alignment will only be required in small increments, for example as the house in which the door is hung settles, hi any case for doors which are closed most ofthe time, most ofthe relative movement between door and frame will happen with the door closed and the latch bolt fully extended into engagement with the contact carrier.

The latch strike with the automatically aligning contact carrier, as shown in Figures 6A and 6B, can be used with the mortise latch described above in relation to Figures 1 A and IB, or the tubular latch of Figures 5 A and 5B , the latter with suitable modification but operating with the same principles. The use of the automatically aligning strike reduces the likelihood that the latch bolt contacts will not make contact with the strike contacts, and can provide for correct alignment of respective latch and strike contacts even when very narrow contacts are used. In an alternative arrangement, not shown, an automatically aligning function is provided on the door rather than on the jamb, h particular, the protruding part ofthe latch bolt is provided with a freedom to move vertically to allow for misalignment between the latch and strike devices. The vertical latch movement may be a rectilinear movement similar to that described above in relation to the auto-aligning strike. Alternatively, the vertical movement ofthe protruding part ofthe latch bolt may be provided by a rotation ofthe latch bolt about a point back within the mortised housing ofthe latch device.

Figures 7A and 7B show yet a further alternative mortise latch. Figure 7A is a plan view ofthe part cross-section at line E-E' of Figure 7B, and Figure 7B is a side elevation view ofthe part cross-section at line F-F' of Figure 7 A.

In Figures 7 A and 7B a mortise latch 101 is mounted in a cutout or mortise 102 in the stile of a door 103. The latch includes a latch bolt 104 with a bevelled or tapered portion. The latch bolt is located in an aperture in a latch face plate 106 which is rebated in the door to present an external surface substantially flush with the surrounding surface ofthe door.

The latch bolt is carried by a latch bolt carrier 107. The carrier and the latch bolt are biassed, by a spring (not shown), toward an extended or protruding configuration, shown in Figures 7A and 7B, in which the distal tapered end of the latch bolt protrudes beyond the face plate 106.

The door is side hung and is mounted in a surrounding jamb 110. When the door 103 closes in the jamb 110, the bevelled face 111 ofthe tapered portion ofthe latch bolt 104 engages a strike 112. The previously protruding portion of the latch bolt momentarily retracts into the latch housing (not shown). When the door is substantially in its closed position and latch bolt is aligned with an aperture 113 in the strike, the latch bolt is urged towards its extended or protruding configuration by the biassing spring and the door is latched closed by interaction between the non-bevelled face 114 ofthe tapered portion of the latch bolt and an edge ofthe aperture in the strike. This latching action is well-known and widely used. A U-shaped contact carrier 115 is attached to the latch bolt by screws or rivets 116. The U-shape may be seen in the plan view of Figure 7A. The contact carrier 115 carries two contact pins 117, one above the latch bolt carrier 107 and one below.

Each contact pin 117 is slidingly supported by the contact canier in two electrically insulating bushes 119 which are mounted in respective arms ofthe U-shape. Respective compression springs 120 are fitted over each contact pin 117 and act against a transverse pin 121 fitted through the contact pin to urge the contact pin outward from the latch in substantially the same direction as the latch bolt is biassed. The contact pins protrude with clearance through apertures 122 in the face plate 106.

A pair of threaded nuts 130 clamp a terminal 131 to a threaded inner end 132 of each contact pin. The terminal is electrically connected by a flexible lead 133 to a sliding contact 134 attached by a electrically insulating mounting 135 to the bridge portion 136 j oining the arms of the U-shaped contact carrier 115.

On each contact pin, one ofthe nuts 130 acts against the adjacent bush 119 as a pin stop, limiting the extent of outward travel ofthe pin.

The sliding contact 134 slides along a spring steel wire contact 137 when the contact carrier 115 moves back and forth with the retracting and extending motion of the latch bolt 104. Each spring wire contact cantilevers from one end which is attached to, but electrically insulated from, a fixed part 138 ofthe latch by an insulated attachment 139 with a connection lug 140 (seen in Figure 7 A) in a manner similar to that described above in relation to the mortise latch of Figures 1 A and IB. Each protruding contact pin 117 is thus electrically connected via the associated terminal 131, flexible lead 133, sliding contact 134, spring wire contact 137, connection lug 140, to a circuit element (such as a lock bolt actuator) within the latch or other device in or on the door.

In Figure 7B the contact carrier 115, the upper spring wire contact and the upper flexible lead, are shown partly broken away to better reveal the pin biassing spring 120, transverse pin 121 and insulating bushes 119. In a similar manner to the mortise latch described above in relation to Figures 1 A and IB, the spring wire contacts shown in Figures 7A and 7B each have an insulating sheath or sleeve over a major portion of their length and an exposed enlarged tip at their distal ends. Thus, the sliding contact makes physical contact with the sleeving when the contact carrier and latch bolt are not fully extended, and only makes electrical contact with the spring wire when the contact carrier is substantially in the fully extended position, ie when the latch bolt is also substantially in the fully extended position as shown in Figures 7A and 7B.

In Figures 7 A and 7B, the strike 112 is mounted in the door jamb 110 and includes contacts 141 mounted to the face plate 142 by insulating bushes 143. The strike contacts are housed within the recess or cutout 144 conventionally provided in the door jamb behind the front plate ofthe strike 112 to accept the protruding tapered end ofthe latch bolt. Some enlargement ofthe recess may be necessary to accommodate the strike contact arrangement.

A lug 146, best seen in Figure 7 A, is provided for connection of the strike contacts to further circuit elements, such as supply lines to a source of power for remote operation of a lock bolt actuator, not shown.

The strike contacts 141 present a diameter greater than that ofthe latch contact pins 117 to allow for a lack of precision in the alignment between the latch and the strike.

As the door is closed the bevelled face 111 ofthe latch bolt 104 engages with the strike 112 to push the latch bolt back into the latch housing. The contact pins 117 are also carried back into the housing so that the pins themselves do not contact the strike. In effect, the spring loaded contact pins 117 are protected by being in the "shadow" ofthe latch bolt, ie they are always positioned back from the outer extent ofthe latch bolt, regardless ofthe degree of extension or retraction ofthe latch bolt.

When the door 103 is closed and the latch bolt 104 extends into the strike recess 144, the latch contact pins 117, carried by the contact carrier 115, are urged by respective biassing springs 120 against the strike contacts 141. The strength ofthe contact springs 120 is less than that of the latch bolt biassing spring (not shown) so that, although the contact pins engage and electrically connect with the strike contacts, the extension of the latch, and therefore the door latching action, is not impeded. The electrical contacts and pins are made from brass but other conductive materials could be used, and may be necessary, for example in corrosive or contaminating environments.

In an alternative arrangement (not shown) spring loaded pins, similar to those described in relation to Figures 7A and 7B, protrude through holes in the latch bolt itself rather than being located above or below the latch bolt.

The mortise latch bolt and latch strike shown in Figures 7A and 7B can be used to provide a connection between the jamb and the door for remotely controlling a door lock and monitoring the status ofthe door and lock. As long as the door is closed and latched, it can be locked or unlocked electrically.

Electric actuation of a door lock used in conjunction with the latch contact arrangements described above can be satisfactorily achieved at a low voltage such as 12 volts and at a peak current of perhaps 3 amperes per lock. This voltage does not present a particular personal hazard. The power supply to the lock would usually be DC rather than AC, particularly with permanent magnet motor actuators which can be reversed from 'locking' to 'unlocking' simply by reversal ofthe polarity ofthe DC supply voltage.

By monitoring the open/closed status ofthe door, voltages or currents that might otherwise present some personal hazard if present on exposed strike contacts in the jamb can be used if automatically removed when the door is not closed.

The strike contacts may be energised when exposed by the open door, but in the strike arrangements described, the strike contacts are recessed into the door jamb and therefore removed from incidental contact by people passing near or through the doorway. The latch bolt contacts, although exposed when the door is open, are not energised and therefore pose no danger.

Figure 7C shows a diagrammatic plan view demonstrating the principle of operation of another arrangement of a latch bolt 300 and a strike 301 which are parts of a latch and strike fitted respectively in a door and frame, not shown. The latch bolt is fitted with an electrically conductive contact 302 which slides within a guide cavity 303 formed in the latch bolt. The cavity is lined with electrical insulation, for example in the form of sleeve 304, to provide electrical isolation between the sliding contact and the latch bolt. In cases where the latch bolt is not electrically conductive, the insulating sleeve may be dispensed with.

The sliding contact is biased outwardly, in direction A, toward the bevelled front face 305 of the latch bolt by a compression spring 306 which is fitted about a reduced diameter portion ofthe shaft 312 ofthe contact.

When the door is closed, the outer bevelled face ofthe latch bolt, or at least an edge ofthe bevelled face, will engage the strike. Outward movement ofthe sliding contact is limited so that the outer end 310 ofthe sliding contact does not protrude beyond the general line ofthe bevelled face ofthe latch bolt and therefore does not engage with the strike as the door is closing. This reduces wear ofthe surface ofthe outer end 310 ofthe sliding contact.

Outward movement of the sliding contact is limited by engagement between a proj ection 311 on the shaft 312 of the contact and a shoulder 313 on the inner wall of the insulated sleeve or, in cases where no sleeve is used, on the wall ofthe guide cavity itself.

The sliding contact has some freedom to move back into the cavity against the bias provided by the compression spring 306.

When the door closes the latch bolt 300 engages the strike 301 and retracts momentarily, generally in direction B, into the latch housing, not shown, before moving in direction A and projecting through an aperture in the strike plate into the cavity 320 of the strike. When in this latched position, the latch bolt, engages a second sliding contact 321 fitted within the strike cavity. This contact is located in the cavity so that when the latch projects into the strike cavity and the back edge 315 of the latch bolt abuts the corresponding edge 322 ofthe strike aperture, the two sliding contacts 302, 321 are aligned.

Alignment in the vertical direction may be facilitated by an automatic alignment contact carrier fitted in the strike and operating in a manner similar to that of the arrangement discussed above in respect of Figures 6 A and 6B. The sliding strike contact 321 is carried in an electrically insulating sleeve 322 and is biased outwardly, in direction B, by a compression spring 323. The insulating sleeve may be dispensed with if the contact carrying part ofthe strike is electrically insulating.

Although the latch and strike combination shown in Figure 8 is shown with two contact biassing springs, only one ofthe latch sliding contact 302 and the strike sliding contact 321 needs to be spring loaded. That is, either one of the biassing spring 306 or 323 may be dispensed with.

A latch and strike can use two ofthe contact arrangements as discussed above and shown in Figure 8 to provide the supply and return paths of an electrical circuit between the associated door and frame. Alternatively, a latch and strike can use one ofthe contact arrangements and utilise the latch bolt itself, where it is electrically conductive, or another of the latch-strike connections described above to provide the supply and return paths of an electrical circuit between door and its associated frame.

Figure 9 shows a diagrammatic side elevation demonstrating the principle of operation of yet another arrangement of a latch bolt 400 and a strike 401 which are parts of a latch and strike fitted respectively in a door and frame, not shown.

When the door is closed, the latch bolt 400 engages the strike 401 and retracts momentarily, generally in direction B, into the associated latch housing before moving in direction A and projecting through an aperture in the strike plate into the cavity 402 ofthe strike. When in this latched position, the latch bolt engages respective first ends of a pair of lever arms 403 fitted within the strike cavity. The levers are pivotally mounted midway their lengths on pivots 405 which are attached to the strike.

A pair of sliding electrical contacts 406, mounted in the strike, are respectively coupled to the second ends of the lever arms. The sliding contacts are mounted in insulated sleeves 407 to provide electrical isolation between the contacts and other parts ofthe strike.

A compression spring 408 biases the first ends ofthe lever arms outwardly, in direction B, toward the aperture in the strike plate. In the absence of engagement ofthe latch bolt with the lever arms, the sliding contacts are generally withdrawn into the strike. A pair of electrical contacts 409 are mounted on the face plate 410 of the latch. These electrical contacts 409 are located adjacent and respectively above and below the latch bolt 400 in positions corresponding to those ofthe sliding strike contacts 406.

When the door is closed the latch bolt 400 engages the first ends ofthe lever arms 403 and compresses the compression spring 408, which is weaker than that biasing the latch bolt outwardly in direction A. As the first ends ofthe lever arms move inward, further into the strike (ie in direction A), the second ends ofthe lever arms and the sliding contacts 406 move in the opposite direction (ie in direction B) to engage and electrically connect with respective latch contacts 409.

A latch and strike can use the contact arrangement of Figure 9 to provide the supply and return paths of an electrical circuit between door and its associated frame. When the door is not closed in the frame, the contacts of both the latch and the strike protrude only slightly beyond their respective surrounding surfaces as shown in Figure 9. In alternative arrangements, not shown, the contacts can be flush or even slightly recessed when the door is not closed.

hi both the arrangements shown in Figures 8 and 9, an electrical contact is advanced across the gap between door and frame when the latch moves outward from the latch housing into the strike cavity, the contact connecting with a corresponding contact provided as part of the strike.

The lever arms 403 are resilient to allow the latch bolt 400 to protrude into the strike cavity to an extent that is not limited by the sliding strike contacts 406 meeting the latch contact 409. Alternatively, resilience can be incorporated into other parts of the anangement, for example at the coupling between the lever arms 403 and the strike contacts 406.

Figures 10 to 20 show various views of latch and strike devices incorporating electrical contacts for coupling electrical energy between a door and a jamb in which the door is mounted. These devices are additional to the contact-carrying latch and strike devices aheady discussed and as shown above, eg in Figures 1, 5 and 8. In the arrangements shown in Figures 10 to 20, the latch-strike couplings provide two conducting paths across the door-jamb gap. The two conducting paths are electrically insulated from one another. Although not discussed in respect ofthe arrnagements shown in Figures 10 to 13 and 17, the latching portion ofthe latch body provides part of one ofthe two conducting paths. This is specifically shown in Figures 14 to 16 and 18 to 20 which show the use ofthe latching portion ofthe latch body as part of one ofthe conducting paths.

Figures 10 and 11 show diagrammatic partial cross-sectional plan views of parts of a rotating end entry latch bolt 500 and an associated strike 501, showing three phases of coupling actions in Figures 10 and three phases of decoupling actions in Figures 11.

Figures 10A, 10B and 10C show a latch device mounted in a door 502, which has closed in a jamb 503. The latch bolt 500 is located in a forend or face plate 504 ofthe latch device mounted in the door 502 and is biassed by a spring toward the aperture in the strike plate 505, as indicated by the arrow in Figure 10A. In Figure 10A the latch bolt, having been pushed into the latch mechanism by engagement with the ramping surface ofthe strike plate as the door closed, has just started to advance into the aperture ofthe strike plate.

A strike contact 506 is carried on a first arm of a carrier 507 which rotates about a pivot 508 in the strike. A second arm ofthe contact carrier is on an opposite side ofthe pivot.

As the latch bolt advances into the strike aperture, as indicated by the arrow in Figure 10B, the latch bolt engages the second arm to begin rotation of the contact carrier. Further advancement of the latch bolt rotates the carrier to bring the strike contact 506 into electrically contacting engagement with a conesponding contact 509 in a well 510 in the latch bolt, as shown in Figure IOC.

The second arm ofthe contact carrier is provided with an L-shaped projection 512 which locates in a similarly L-shaped second well 513 in the latch bolt when the latch bolt engages the contact carrier.

Figures 11 A, 1 IB and 11C show the latch device being disengaged from the strike, eg in preparation for opening ofthe door. Upon initial disengagement ofthe latch bolt from the strike, in a direction as indicated by the arrows in Figures 11, the L-shaped second well 513 engages the distal arm ofthe L-shaped projection 512, as shown in Figure 11A, to rotate the contact carrier in a reverse direction, opposite to the contact-engaging rotation described above. This reverse rotation disengages the strike contact 506 from the conesponding contact 509 in the latch bolt, as shown in Figure 11B. The latch bolt then withdraws further, as shown in Figure 11 C, until it is free from the strike and the door unlatched ready for opening-

Figure 12 shows a perspective view of a side entry latch bolt 515. A resilient electrical contact 516 is provided in cavity 517 in the bevelled or rounded end face 518 ofthe latch bolt.

Figures 13 A, 13B and 13C show diagrammatic partial cross-sectional plan views of parts of the side entry latch bolt of Figure 12 and an associated strike, showing phases of a coupling action. Figure 13 A shows the side entry latch bolt 515 advancing outward from a forend 519 of a latch device fitted in a door 520 which has almost closed, the closing direction being indicated by arrow C.

The strike has an L-shaped contact carrier 521 which is spring biassed outwardly toward the latch device. Just before the door reaches its closed position, the latch advances part way into the strike, as shown in Figure 13 A.

With further closing movement of the door, in direction C, the distal arm 522 of the L- shaped contact carrier is accepted into the cavity 517 in the end face ofthe latch bolt. A contact 523 on the carrier 521 makes electrical contact with the electrical contact 516 in the cavity 517 ofthe latch bolt, as shown in Figure 13B. The latch bolt has a tapered portion between the cavity 517 and the outer bevelled face 518. An inside face on the tapered portion of of the cavity 517 pushes the distal arm 522 against the contact 516 as the door completes its closing movement.

When the door reaches its closed position, the latch bolt advances further, in direction D, into the strike to engage with an edge 524 ofthe strike aperture to latch the door closed. This further advancement ofthe latch bolt into the strike moves the strike contact carrier into the strike against the spring biassing, to increase the engagement pressure between the strike and latch bolt contacts, as shown in Figure 13C. Figures 14A, 14B and 14C show diagrammatic partial cross-sectional plan views of parts of a first type of end entry latch bolt 530 and an associated strike 531, showing phases of a coupling action. Figure 14A shows latch device in a door 532 that has just closed in a direction shown by the arrow E. The latch bolt, by engagement with the ramping surface ofthe strike plate 533 has been partially pushed into the latch device.

hi Figure 14B, the latch bolt, having reached the end ofthe ramping surface, is advancing into the strike aperture, as indicated by arrow F. A cavity 534 in the outer bevelled or rounded end 535 ofthe latch bolt houses a resilient female electrical contact 536 which is electrically insulated from the remainder of the latch bolt. This cavity is similar to the cavity 517 ofthe latch bolt of Figure 12.

As the latch bolt of Figures 14 advances into the strike in direction F, the latch bolt contact 536 is engaged by a male contact 537 provided in the strike. A resilient second strike contact 538 makes electrical contact with an outer face 539 of the latch bolt when it is located within the strike aperture.

Figure 14C shows the latch bolt as fully extended into the strike aperture.

Figure 15 shows a perspective view of a second type of end entry latch bolt 540. A resiliently hinging flap contact 541 is provided in a cavity 542 in the bevelled or rounded end face 543 ofthe latch bolt. The flap contact is electrically insulated from the remainder ofthe latch bolt.

Figures 16A, 16B and 16C show diagrammatic partial cross-sectional plan views of parts ofthe second type of end entry latch bolt 540 of Figure 15, as part of a latch device 544 and fitted to a door 545, in association with a strike 546, showing phases of a coupling actions.

Figure 16A shows the latch device 544 in the door 545 that has just closed in a direction shown by the arrow H. The latch bolt, by engagement with the ramping surface of a strike plate 547 has been partially pushed into into the latch device.

In Figure 16B, the latch bolt, having reached the end ofthe ramping surface, is advancing into the strike aperture, as indicated by arrow I. As the latch bolt of Figures 16 advances into the strike in direction I, the latch bolt contact 541 is engaged by a contact 548 provided in the strike. A resilient second strike contact 549 makes electrical contact with an outer face 550 of the latch bolt when it is located within the strike aperture.

Figure 16C shows the latch bolt as fully extended into the strike aperture and shows the resilient latch and strike contacts reoriented against their resilience under pressure from the respective non-resilient strike and latch contacts.

The latch-door coupling arrangements discussed herein accommodate variations in the gap between frame and door. For example, this gap is shown as dimension G-G' in Figures 14A, 14B, 16A and 16B which show the gap as a large gap, whereas in Figures 14C and 16C the corresponding gap is shown at a minimum.

The arrangements shown in Figures 10, 13, 14 and 16 are resistant to tamper attempts.

While the door is closed it is difficult to access the contacts, from either side ofthe door, in an attempt to defeat any associated lock control system. It is difficult to access the contacts from outside a building with either inward or outward opening doors when fitted with such a system. Tamper resistance may be further enhanced by using sliding contact- breaking latch connections as discussed above and shown in Figures 2 to 4.

Figure 17 shows a perspective view of a third type of end entry latch bolt 555, and an associated strike contact assembly 556.

The latch bolt 555, as shown in Figure 17, has a slot 557 through the full thickness of its bevelled or rounded end 558. A U-shaped female contact 559 is located in the slot but electrically insulated from the latch bolt itself. A conductor 560 provides an electrical connection to the U-shaped latch bolt contact.

The strike contact assembly 556, as shown in Figure 17, has a male contact 561 mounted between the arms of a U-shaped contact support 562. The strike contact 561 is electrically insulated from the support 562 and has a leading edge 563 from which two trailing contact leaves 564 depend in a V-shaped configuration. The strike contact 561 is resilient about its leading edge 563 to maintain contact pressure and provide an allowance for misalignment, between the latch bolt contact 559 and the leaves 564 of the strike contact 561.

The latch bolt advances into the aperture in the strike in the direction indicated by arrow J so that the U-shaped latch bolt contact 559 straddles and contacts the strike contact 561.

The strike contact assembly is not rigidly mounted in the door jamb. It is able to move in directions indicated by areow K so that the strike contacts can align with the contact in the latch bolt slot.

hi a variation, not shown, ofthe contact arrangement shown in Figure 17, two electrically isolated contacts are provided on respective sides ofthe slot in the latch bolt, and the strike contact assembly carries two electrically isolated contacts. This variation provides two electrical paths across the door-jamb gap to allow for a complete electrical circuit.

Figure 18 shows an end elevation view of a strike 570 with a rotating contact assembly 571 for use with the end entry latch device 572 shown in an end elevation view in Figure 19. Figures 20A, 20B and 20C show partial cross-sectional plan views ofthe end entry latch device 572 and the associated strike 570, showing aspects of a coupling action. The arrows A, in Figure 20 A, indicate the line and direction ofthe end elevation view ofthe strike in Figure 18. The end elevation view of the latch device in Figure 19 is in the opposite direction.

The strike contact assembly includes a U-shaped strike contact 573 made of a spring metal which is located in the strike. A second strike contact 574, electrically insulated from the U-shaped contact, is carried on the inside face of one arm ofthe U-shaped contact.

When the latch is engaged in the strike as seen in Figure 20C, the other arm of the U- shaped contact makes electrical contact with the outer surface 575 ofthe body ofthe latch bolt 576, and the second strike contact 574 makes electrical contact with a contact 577 bonded to, but insulated from, the latch bolt at one side of a cavity 578 in the latch bolt.

As best seen in Figure 18, the second strike contact 574 is narrower than the U-shaped strike contact 573. This improves the mechanical shielding ofthe second strike contact against attempts to access both conductive paths between strike and latch, such as when trying to defeat an electrically actuated lock powered or controlled via the contacts. For further resistance against tampering, the latch bolt device can include sliding contact- breaking connections, eg as discussed above in relation to Figures 2 to 4.

The gap A, shown in Figure 20B, between the strike contacts 573, 574, is somewhat smaller than the dimension B between the faces ofthe latch bolt contacts 575, 577. Either or both ofthe strike contacts are resilient, or springy, so that contact pressure is maintained once the strike and latch bolt are engaged.

The strike contact assembly 571 is pivotally mounted on a shaft 578. The strike contact assembly rotates about the shaft so that relative movement or misalignment between door and strike, in the door opening and door closing directions (eg door rattle), can be tolerated. Rotation ofthe strike assembly is limited in one direction by abutting a stop 579 and in the other direction by abutting an edge 580 (best seen in Figure 20C) of the aperture in the strike plate. The strike contact assembly is biased by a spring, not shown, in a clockwise direction as viewed in Figures 20.

The second strike contact 574 is shaped to present a rounded surface to the corresponding latch bolt contact 577 so that electrical contact is maintained over the full range of rotation ofthe strike contact assembly.

The vertical dimension of the cavity 578 in the latch bolt is sized larger than that ofthe strike contact assembly to tolerate vertical misalignment between the latch bolt and strike contact assembly.

Figures 21 A and 21B show a latch by which energy is transferred between jamb and door by electromagnetic coupling.

A latch bolt 200 is fitted to a door 201 (shown only by a minimal outline). The latch bolt consists of a generally C-shaped magnetic half-core 202. The latch bolt half-core 202 is biassed by a spring (not shown) toward a position in which a snub nosed tapered portion 203 (best seen in Figure 21 A) protrudes from the outer edge 204 ofthe door. The latch bolt can retract back into the door, against the spring biassing, substantially rectilinearly in direction shown by arrow A. An electrical latch coil 205 surrounds one arm 206 of the C-shaped latch half-core 202. The coil is elongated in direction A to accommodate the retracting movement of the latch bolt half-core while the coil itself remains stationary in the door.

The outer end ofthe latch half-core 202 protrudes from the door 201 like a conventional latch bolt and is both tapered and snub-nosed. The snub nose 203 enables a greater cross- section of magnetic material to be present in the core.

The latch bolt half-core 202 engages a strike 210 mounted in the surrounding jamb (not shown) in which the door 201 is hung. A strike half-core 211 is mounted within a strike recess 212 behind the front plate 213 of the strike. The strike half-core is generally C- shaped and, as best seen in Figure 21 A, presents a surface 214 shaped to matingly engage with the corresponding outer end faces 215 presented by the latch bolt half-core. An electrical strike coil 216 sunounds an arm 217 of the strike half-core.

The strike half-core in the jamb and the latch bolt half-core in the door form a magnetically coupled circuit when the door is closed and the latch bolt half-core protrudes into the strike recess to mate with the strike half-core. The coils and half-cores, when magnetically coupled such as when the door is closed and latched, act in the manner of an electrical transformer, transferring electrical energy between jamb and door.

The half-cores are made from a suitable material having high magnetic permeability at the frequencies ofthe alternating magnetic fields to be induced. The half-cores are constructed from laminations made from armature iron. Other magnetic materials may be used.

Figure 21 A shows the door 201 ajar. An electrical current in the strike coil 216 will induce a magnetic field in the strike half-core 211 but negligible magnetic flux will link with the latch half-core 202 and negligible voltage or current will be induced in the latch coil 205.

The stationary strike half-core 211 is shaped to receive the tapered snub nosed protruding part 203 of the latch bolt half-core 202 with maximum contact area so as to reduce the reluctance across the gap between the two half cores when the door is latched. When the door closes in the direction shown by the arrow B, the latch bolt half-core 202 engages the front plate 213 of the jamb-mounted strike 210. As the door closes, the latch bolt half-core is momentarily pushed back into the door against the biassing spring (not shown) by engagement with the strike plate 213.

As the door reaches the fully closed position as shown in Figure 21B, the end portion 203 of the latch bolt half-core 202 is pushed by the biassing spring (not shown) through the aperture in the strike plate 213 into the strike recess 212 behind the strike plate to matingly engage with the stationary strike half-core 211 mounted within the strike recess, so completing a magnetic circuit. In this situation an alternating current in either coil will induce a corresponding alternating voltage or current in the other.

By this means a current in the strike coil 216 in the jamb can induce a current in the latch coil 205 in the door thereby transferring power from jamb to door to actuate a lock, for example by driving a lock bolt actuator. The transformer coupling between the jamb and door can also be used to transfer status monitoring and signalling, for example by modulating the AC current applied to a respective coil, or by applying a direct current to bias the magnetic hysteresis loop of one ofthe half-cores.

Vertical misalignment between the two half-cores can be reduced by an auto-aligning strike half-core carrier (not shown), in a manner similar to that described above in relation to the auto-aligning contact carrier of Figures 6 A and 6B.

Spaces between the outer arms ofthe C-shaped half cores reduce the likelihood that the magnetic flux originating from one coil will bypass the other if vertical misalignment occurs. Inserts 218, 219 made of low permeability material fill the spaces between the outer arms ofthe C-shaped half cores.

In modifications ofthe contact arrangements discussed above and shown in Figures 7A, 7B, 8 and 9, power and/or signalling circuits are coupled across the jamb/door interface without use of electrical contacts. In these modifications, instead of electrical conductors being brought into contact across the gap between door and jamb, halves of an electromagnetic coupler are bought into sufficiently close proximity to provide magnetic coupling between respective electromagnetic half cores to complete the coupling between respective electrical circuits in the jamb and door. The electromagnetic half couplers are transformer halves comprising respective windings on half cores made, for example, from iron laminations or from ferrite material.

The respective half cores are mounted with one being moved by latch bolt movement, similarly to the contacts shown in Figures 7 A, 7B, 8 and 9. In a manner similar to the arrangements in Figure 7 A, 7B and 8, one half core is mechanically retracted into the latch housing by movement ofthe latch bolt into the latch housing, but is allowed to advance out across the door-jamb gap when the latch bolt protrudes into the aperture in the strike plate. Alternatively, in a manner similar to the arrangement in Figure 9, one half core is mechanically retracted behind the strike plate by a bias spring but advanced across the door-jamb gap, toward a complementary half core mounted on the door, when the latch bolt extends into the aperture in the strike plate.

Thus the transformer coupling halves can be brought into close physical proximity to provide effective close-coupled transformer action to ensure effective coupling between signalling and power circuits on opposite sides ofthe interface between jamb and door gap. By coupling movement of at least one of the transformer coupling halves to latch bolt movement the transformer halves can be brought to closer coupling, and can more readily accommodate normally expected variations in door-jamb gap, than if merely mounted in a fixed manner on door and jamb or strike.

It is to be noted that the transformer halves do not need to be brought into intimate contact. The magnetic coupling arrangements described herein can be used, even without close coupling, to reduce the reluctance of the magnetic coupling across the door-jamb gap, and/or to reduce leakage flux or stray magnetic fields, which may affect people or their possessions when nearby or passing through the doorway. A low level magnetic coupling, even if not coupling sufficient power to activate the lock directly, can be used to trickle charge an on-door battery that can then provide sufficient power.

The use of transformer halves to provide signal and power coupling in modifications ofthe arrangements shown Figures 7A, 7B, 8 and 9 is to be distinguished from the electromagnetic coupling arrangement described above and shown in Figures 21 A and 21B where one of the half couplers is the latch bolt itself and is shaped accordingly with a bevelled face and is urged outward by a biassing spring to engage a complementary half coupler located in the strike plate.

Figures 22 and 23 show respective side and underside plan views of an example of a pair of transformer halves providing coupling of energy across the door jamb gap, where one transformer half is mechanically coupled to the latch bolt so that movement ofthe latch bolt provides movement ofthe transformer half.

In Figures 22 and 23 a first transformer half 600 is mounted behind the front plate 601 of a strike 602. A co-operating latch device 603 includes a latch bolt 604 which extends from, and is retractable into, a latch housing (not shown) through a forend or face plate 605 ofthe latch device. A second transformer half 606 is located in the latch housing and is mechanically coupled to the latch bolt by a pair of parallel arms 611. Respective ends of the arms are pivotally attached to the latch bolt and second transformer half so that the second transformer is constrained to move substantially linearly relative to the latch bolt while being maintained parallel thereto.

The arms are linked by a tension spring 607 in a manner that biasses the second transformer half outward from the latch housing. A projection 608 on the second transformer half abuts a peg 609 on the latch bolt to movement ofthe second transformer half, relative to the latch bolt. This abutment constrains the outward projection ofthe transformer from the latch housing to be always less than that of the latch bolt. The second transformer half thus moves back and forth with latch bolt movement but always remains in the 'shadow' ofthe latch bolt. By this means, the second half transformer 606 never makes contact with the strike front plate 601.

Figure 22 A shows the latch bolt 604 and second transformer half 606 adjacent, but disengaged from, a strike 602.

Figure 22B shows the latch bolt 604 and second transformer half 606 engaged with the strike 602; the second half transformer 606 in transformer coupling enagement with the first transformer half 600. The anangement of parallel arms and spring biassing allows the latch bolt to continue moving into further engagement with the strike even after the transformer halves have abutted one another.

The transformer halves are provided with bevelled faces that encourages self-cleaning. As may be best seen in Figure 23 A, the bevelling ofthe face ofthe second transformer half allows it to fit within the 'shadow' ofthe latch bolt, ie behind the bevelled or rounded end face ofthe latch bolt.

The first and second transformer halves have respective windings on half cores made, for example, from iron laminations or from ferrite material.

Thus the transformer coupling halves 600, 606 can be brought into close physical proximity to provide effective close-coupled transformer action to ensure effective coupling between signalling and power circuits on opposite sides ofthe interface between jamb and door. By coupling movement ofthe second transformer half to latch bolt movement, the transformer halves can be brought to closer coupling, and can more readily accommodate normally expected variations in door-jamb gap 610, than if merely mounted in a fixed manner on door and jamb or strike.

The electrical contact and transformer coupling arrangements discussed above may be used to transfer energy at a low power level to provide a trickle charge for on-door rechargeable batteries, that when charged, provide suffient power to actuate a lock. Such arrangements avoid the need for the transfer across the door-jamb interface ofthe high power needed for lock actuation.

The energy coupling arrangements discussed herein may be used with lock actuation mechanisms having distinct lock and unlock commands and which do not require continuous energisation to maintain a lock or unlock condition. The electrical contact anangements can couple energisation of opposite polarities to control respective lock and unlock operations.

It is to be understood that while there may be no energisation ofthe lock actuator unless it is performing a lock or unlock operation, there may be electrical energisation of status monitoring circuits within the door or more particularly within the lock. The status monitoring circuits may be permanently energised, or only energised for short periods at intervals, for example for a few milliseconds every second to effectively provide continuous monitoring.

The latch bolt connections provided between jamb and door for the transfer of power to a lock, for example to energise the lock's electric motor, solenoid, or other actuation means, can also be used for transferring lock and door status monitoring signals. It is clear that only a small number of insulated conducting paths can practically be carried directly by a latch bolt. Coupling arrangements described allow for two conducting paths or superimposed signals to be used for both actuation and status monitoring functions. Typical auxiliary signalling could include status monitoring functions such as door open/closed status and door locked/unlocked status, or might serve ancillary functions such as enabling a door mounted bell push to activate a remote door chime.

The embodiments shown in Figures 1 A, IB, 5A, 5B, 7A, 7B, 21 A and 21B can cope with variations in the horizontal gap between the outer face ofthe strike or door jamb, and the outer face or forend ofthe lock in the outer end face ofthe door, when closed. In practical installations this gap can typically be between 0 mm and 6 mm. By moving the energy couplers (such as the electrical contacts or the electromagnetic latch half-core) as part of the latch bolt assembly, the energy couplers are advanced across the gap toward the strike until they mate with the corresponding coupler in the strike recess, allowing the coupling of energy to be achieved for a range of door/jamb gaps.

While one application for the embodiments described is in central locking of houses, the embodiments apply equally well to other situations where it is desired to convey electrical energy and/or information between a door and its jamb.

The application of the embodiments described is not limited to tapered or bevelled end latch bolts on single leaf side hung doors but may be applied to a variety of other types of latches on other types of doors. Some other examples include expanding latch bolts, hook latches, French doors (multiple leaf side hung), and sliding doors. Neither is the application ofthe embodiments limited to doors and their surrounds; it may also be applied to any similarly disposed pair of parts capable of similar relative movement. Where in the foregoing description reference has been made to integers or components having known equivalents then such equivalents are herein incorporated as if individually set forth.

It is to be understood that the scope of the invention is not limited to the described embodiments which have been given by way of example and therefore that variations and modifications may be made to these embodiments without departing from the scope ofthe invention as set out in this specification.

Claims

1 A latch means including a support and a latch bolt, the latch bolt being moveable relative to the support, between a protruded position in which a portion ofthe latch bolt protrudes from the support and a retracted position in which the portion of the latch bolt is substantially retracted behind the support, characterised in that the latch means also includes at least one energy coupler, the or each energy coupler being moveable relative to the support between an extended position in wliich a portion ofthe coupler extends from the support and a withdrawn position in which the portion ofthe coupler is substantially withdrawn behind the support, the or each coupler being mechanically associated with the latch bolt so that the or each coupler is moved from the withdrawn position toward the extended position by movement of the latch bolt from the retracted position toward the protruded position and the or each coupler is moved away from the extended position to the withdrawn position by movement of the latch bolt from the protruded position to the retracted position.

2 A latch means as claimed in claim 1 wherein the latch bolt is moveable substantially rectilinearly between the protruded position and the retracted position.

3 A latch means as claimed in claim 1 or 2 wherein the latch means includes an energy coupler which is an electromagnetic coupler.

4 A latch means as claimed in claim 3 wherein the electromagenetic coupler is a half transformer having a core and a winding.

5 A latch means as claimed in claim 4 wherein the latch bolt is the electromagenetic coupler.

6 A latch means as claimed in claim 4 wherein the half transformer is mechanically attached to the latch bolt but moveable relative to the latch bolt.

7 A latch means as claimed in claim 1 or 2 wherein the or each energy coupler is an electrical conductor. 8 A latch means as claimed in claim 7 wherein at least one ofthe electrical conductors is attached to, but electrically insulated from, the latch bolt.

9 A latch means as claimed in claim 8 wherein the portion of the latch bolt has a bevelled face for co-operating in use with a strike, and at least one of the electrical conductors is fixed to the latch bolt and exposed on the bevelled face.

10 A latch means as claimed in claim 8 or 9 wherein the portion ofthe latch bolt has a bevelled face for co-operating in use with a strike, the portion ofthe latch bolt has a non- bevelled face opposite the bevelled face, and at least one of the electrical conductors is fixed to the latch bolt and exposed on the non-bevelled face.

11 A latch means as claimed in claim 8 wherein at least one ofthe electrical conductors is resiliently mounted on the latch bolt and resiliently biased toward the extended position.

12 A latch means as claimed in any one of claims 7 to 11 wherein at least one ofthe electrical conductors makes electrical connection with a respective electrical contact mounted to the support, the connection being made at least when the energy coupler is substantially at the extended position.

13 A latch means as claimed in claim 12 wherein each of said electrical conductors making electrical connection makes electrical connection with the respective electrical contact at least when the energy coupler is at any position between the extended position and an intermediate position being part way between the extended position and the withdrawn position.

14 A latch means as claimed in claim 13 wherein each of said electrical conductors making electrical connection makes electrical connection with the respective electrical contact when the energy coupler is at any position between and including the extended position and the withdrawn position.

15 A latch means as claimed in claim 12 wherein each of said electrical conductors making electrical connection at least when the energy coupler is substantially at the extended position, does not make electrical connection with the respective electrical contact when the energy coupler is not substantially in the extended position.

16 A latch means as claimed in claim 15 wherein each electrical contact is elongated and is insulated over a portion of its length and the respective electrical conductor physically contacts the insulated portion and does not make electrical connection with the contact when the respective energy coupler is not substantially in the extended position.

17 A latch means as claimed in any preceding claim wherein the latch means is fitted to a door surrounded by a door jamb, and at least one ofthe energy couplers forms part of a circuit by which energy can flow between the latch means and the jamb, when the door is latched in the jamb.

18 A latch means as claimed in claim 17 wherein the support carries a locking means and a lock-unlock actuator by which the locking means may be actuated to change between a locked configuration and an unlocked configuration, and the lock-unlock actuator can be powered to actuate the locking means by energy flowing between the jamb and the lock- unlock actuator, when the door is latched in the jamb.

19 A latch means as claimed in claim 17 wherein the latch means is fitted to a door, and the door is also fitted with a locking means that is distinct from the latch means, the locking means having a lock-unlock actuator by which the locking means may be actuated to change between a locked configuration and an unlocked configuration, and the lock-unlock actuator can be powered to actuate the locking means by energy flowing between the jamb and the lock-unlock actuator via the latch means, when the door is latched in the jamb.

20 A latch means as claimed in any one of claims 7 to 19 wherein the latch bolt is one ofthe electrical conductors.

21 A strike means for use with a co-operating latch means, the strike means having a strike plate, characterised in that the strike means is for co-operating with a latch means having at least one electrical conductor, and the strike means has at least one electrical contact located for respective electrically-contacting engagement by the at least one electrical conductor ofthe co-operating latch means. 22 A strike means as claimed in claim 21 wherein the strike means includes a contact carrier and the at least one electrical contact is resiliently mounted on the contact carrier.

23 A strike means as claimed in claim 22 wherein the contact carrier includes a pivot pin and the at least one electrical contact is mounted for resilient rotation about the pivot pin.

24 A strike means as claimed in claim 22 or 23 wherein the contact carrier is movable relative to the strike plate and the contact carrier includes a bevelled surface against which in use a latch bolt of the co-operating latch means can act to move the contact carrier relative to the strike plate to reduce misalignment between the latch bolt and the contact carrier.

25 A contact pair including first and second electrical contacts, the first contact being moveable relative to the second contact in a substantially rectilinear direction from a first relative position to a second relative position, and the contacts being in mutual electrical connection at least when the first contact is substantially at the first relative position, wherein the second electrical contact is elongated and cantilevered from an attachment point at one of its ends.

26 A contact pair as claimed in claim 25 wherein the contacts are in mutual electrical connection when the first contact is at any relative position between the first relative position and an intermediate relative position being part way between the first and second relative positions.

27 A contact pair as claimed in claim 26 wherein the second contact is electrically insulated over a portion of its length and the first contact physically contacts the insulated portion and does not make electrical connection with the second contact, when the first contact is substantially at any relative position between the intermediate relative position and the second relative position.

28 A contact pair as claimed in claim 25 wherein the contacts are in mutual electrical connection when the first contact is at any relative position between and including the first and second relative positions. 29 A contact pair as claimed in claim 25 wherein the contacts are not in mutual electrical connection when the first contact is not substantially at the first relative position.

30 A contact pair as claimed in claim 29 wherein the second contact is electrically insulated over a portion of its length and the first contact physically contacts the insulated portion and does not make electrical connection with the second contact, when the first contact is not substantially at the first relative position.

31 A latch strike having a frame by which the strike may be attached to a door j amb, and a carrier for carrying a part of at least one energy coupling pathway, the carrier being attached to the frame by an attachment means, wherein movement ofthe carrier relative to the frame in two of three orthogonal directions is restrained while being allowed in the third orthogonal direction.

32 A latch strike as claimed in claim 31 wherein the carrier is U-shaped with two limbs extending from a portion linking the proximal ends ofthe two limbs, and attachment ofthe carrier to the frame is by way ofthe linking portion.

33 A latch strike as claimed in claim 32 wherein the distance between the inside faces ofthe limbs ofthe U-shaped carrier increases toward the distal ends ofthe limbs.

34 A latch strike as claimed in claim 31 wherein the carrier is moveable in the third orthogonal direction in response to an externally applied force and, in the absence of an externally applied force, the carrier is retained by the attachment means in a fixed position relative to the frame.

35 A latch strike as claimed in claim 31 wherein the frame has one or more slots oriented in the third orthogonal direction and the attachment means is at least two fasteners which are slidingly fitted in at least one ofthe slots.

36 A latch strike as claimed in claim 31 wherein the carrier supports at least one electrical contact, the contact being electrically insulated from the carrier and frame.