[0001 ] This invention relates to an electric strike for use with a door latch assembly. The electric strike is of the kind having a keeper that pivots relative to a housing between an open position and a closed position, with a biasing means urging the keeper towards the closed position.

[0002] An electric strike is normally mounted in a door frame so as to interact with a latchbolt assembly mounted to the associated door. The electric strike includes a strike plate or keeper that engages with the latchbolt when the door is in the closed position. The keeper is pivotable when the electric strike is in an unlocked condition, so as to release the latchbolt and allow the door to move from the closed position. Whereas the keeper is prevented from pivoting when the electric strike is in the locked condition so as to inhibit movement of the door from the closed position.

[0003] An electric strike will include some form of lock mechanism, with a powered actuator, to inhibit pivoting of the keeper from the closed position when the lock mechanism is in the locked condition. One form of lock mechanism known to the applicant includes a powered actuator in the form of a solenoid, having a plunger that moves relative to the housing in response to power being supplied to the solenoid. The movement of the plunger moves a plurality of pins in one direction relative to a shear plane between the keeper and the housing. The pins can be moved in the opposite direction back to their original positon under the influence of a spring acting on the pins, once the supply of power to the solenoid ceases. When one of the pins extends across the shear plane, the keeper is inhibited from moving relative to the housing. It also ought to be appreciated that the keeper can move to the open position once none of the pins extend across the shear plane.

[0004] The lock mechanism of the electric strike can be configured so that without the supply of power to the solenoid one of the pins extends across the shear plane, while the supply of power causes the plunger to move the pins such that none of the pins extends across the shear plane. This mode of operation is often referred to as fail secure, whereby in a power failure event the lock mechanism remains in a locked condition. Furthermore the lock mechanism may be reconfigurable such that without the supply of power to the solenoid none of the pins extends across the shear plane, while the supply of power causes the plunger to move the pins such that one of the pins extends across the shear plane. This mode of operation is referred to as fail safe, whereby in a power failure event the lock mechanism remains in an unlocked condition.

[0005] The solenoid of the lock mechanism is often fastened to the housing in such a way that it can be moved in order to configure the lock mechanism to operate in either fail safe or fail secure mode. It is generally desirable for the lock mechanism to include three pins in series in order allow for the lock mechanism to be capable of adopting either the fail safe mode or the fail secure mode. If the fastening of the solenoid to the housing comes loose during the normal operation of the electric strike, this may cause the lock mechanism to unintentionally adjust the position of the pins and thereby adjust the mode.

[0006] When the keeper is in the closed position, the series of pins are axially aligned to move freely within a bore extending between the keeper and the housing. However when pressure is applied by a user to open the door before power is supplied to the solenoid, the portion of the bore in the keeper can be misaligned relative to the portion of the bore in the housing. This can cause the pin extending across the shear plane to slightly pivot off axis and jam, resulting in the solenoid being unable to apply enough force to move the pins within the bore. This issue is often referred to as preload.

[0007] The issue of preload, and even load on the door alone, can cause other serviceability issues with electric strikes, particularly where the shear plane is at one end of the keeper. Where one end of the keeper is fixed relative to the housing by one of the series of pins extending across the shear plane, and load is applied to the door, the keeper itself and its position relative to the housing can be distorted. After repeated load and preload episodes, the positon of the bore in the keeper can be misaligned relative to the bore in the housing which inhibits or prevents movement of the pins. [0008] The axial arrangement of the solenoid and pins relative to the keeper, while leaving sufficient room for the plunger to move the pins relative to the keeper, generally results in an elongated housing. The housing can as a result be twice as long as the length of the keeper. The applicant has appreciated that architects and those specifying electric strikes for security solutions desire more compact options.

[0009] A reference herein to a patent document or other matter which is given as prior art is not to be taken as an admission that that document or matter was, in Australia, known or that the information it contains was part of the common general knowledge as at the priority date of any of the claims.

[0010] According to one aspect of this invention there is provided an electric strike for use with a door latch assembly when mounted to a door including, a housing, a keeper that is movable relative to the housing between an open position and a closed position with a keeper biasing means urging the keeper towards the closed position, a lock mechanism including a powered actuator, the lock mechanism being adjustable between a lock condition and a release condition when the keeper is in the closed positon so that the keeper is inhibited from moving from the closed position when the lock mechanism is in the lock condition and movable from the closed position when the lock mechanism is in the release condition, the lock mechanism including a first detent member and a second detent member that are each movable, the first detent member is movable relative to the second detent member from a first position to a second position when the lock mechanism is in the release condition and the keeper moves between the closed positon and the open position, and when the lock mechanism is in the lock condition with the keeper in the closed position the first detent member and the second detent member both engage the keeper and are inhibited from moving from the first position to the second position so as to hinder the keeper from moving from the closed position.

[0011 ] In a preferred embodiment the electric strike includes a first interface between the keeper and the housing and a second interface between the keeper and the housing when the keeper is in the closed positon, when the first detent member and the second detent member are in the first position they each extend across the first interface and second interface respectively when the keeper is in the closed position and when first detent member and the second detent member are in the second position they are each adjacent the first interface and second interface respectively when the keeper is in the open position. The first interface and second interface may include any plane, zone or region that exists between the keeper and the housing when the keeper is in the closed positon. Where both the keeper and housing have a pair of opposing faces which are aligned perpendicular to an axis about which the keeper moves, the first interface and the second interface might each include a respective plane that is perpendicular to the axis. Alternatively the opposing faces of the keeper and housing may be at an angle to the axis.

[0012] It is preferred that the electric strike be adapted to control movement of the first detent member relative to the second detent member. The manner in which this may be achieved preferably includes an articulated member acting between the first detent member and the second detent member, which is adjustable between an extended condition and a retracted condition as the first detent member and the second detent member adjust from the first position to the second position. The articulated member preferably pivots about a movable axis that moves relative to the housing as the articulated member adjusts between the extended condition and the retracted condition. The electric strike preferably includes a guide formation which interacts with the articulated member so that the articulated member pivots about the movable axis that moves linearly relative to the housing. The guide formation preferably limits movement of the articulated member when it is in the extended condition so that urging the keeper to move from the closed position towards the open position urges the articulated member to move towards the retracted condition. It is further preferred to include a detent biasing means urging each of the first detent and second detent to adopt the second position. The detent biasing means may act on the articulated member urging it towards adopting the retracted condition. The lock mechanism may also include a movable abutment that is adjustable on operation of the powered actuator to move between an active position and an inactive position in which it prevents and does not prevent respectively movement of the articulated member from the extended condition to the retracted condition. The abutment may pivot about an abutment axis between the active position and the inactive position. The abutment includes an abutment surface spaced from the abutment axis, the abutment surface interacting with the articulated member so that urging the articulated member towards the retracted condition creates a force that acts on the abutment in a direction substantially perpendicular to the abutment axis.

[0013] The electric strike preferably includes a controller mounted within the housing which controls supply of power to the powered actuator and monitors signals received from a keeper sensor so as to prevent supplying power to the powered actuator while the keeper is in the open position. It is preferred that the electric strike include a power storage device within the housing for providing power at least to the controller. The preferred form of power storage device is a super capacitor, however other forms of power storage devices are clearly possible.

[0014] The power storage device is preferably mounted on the controller and in a power failure event from a main power source, provides power to the controller. The controller is preferably operable in a fail-safe mode whereby in the event of the power failure event the power storage device provides power to the controller so as to adjust the condition of the lock mechanism to the release condition, or in a fail secure mode whereby in the event of the power failure event the power storage device provides power to the controller so as to adjust the condition of the lock mechanism to the locked condition provided the keeper is in the closed position. The electric strike preferably includes a switch which is adjustable from outside the housing for adjusting operation of the controller between the fail-safe mode and the fail-secure mode. The switch may be operable at a front face of the housing so that the operation of the controller can be adjusted when the electric strike is mounted. However when the switch is located in this position it is preferred that access to the switch be obstructed by a faceplate or other similar member attached to the housing. Alternatively the switch may be located elsewhere on the housing which is obstructed by the door jamb when the electric strike is installed. Arranging the switch in this manner reduces the ability for the mode to be adjusted once the electric strike is installed which it makes it more difficult to tamper with. [0015] The electric strike preferably includes a number of sensors to record the position of the various moving components of the electric strike. This may include a keeper sensor, preferably in the form of a hall sensor and the keeper includes a magnet which is sensed by the hall sensor when the keeper is in the closed position. The keeper sensor is preferably mounted to the controller.

[0016] The powered actuator may take any suitable form, and one preferred form includes an electric motor and a drive shaft that rotates about an actuation axis when energised. The controller is preferably adjustable in supplying power to the electric motor so as to adjust between operating in a forward mode and a reverse mode so as to rotate the drive shaft in a clockwise and anti-clockwise direction. The powered actuator also preferably includes a shuttle that is moveable relative to the housing on rotation of the drive shaft. The shuttle is adapted to interact with the abutment so that movement of the shuttle causes the abutment to pivot about a fixed axis.

[0017] According to another aspect of this invention there is provided an electric strike for mounting to a door jamb to use with a door latch assembly when mounted to a door including, a housing, a keeper that is movable relative to the housing between an open position and a closed position with a keeper biasing means urging the keeper towards the closed position, a lock mechanism including a powered actuator including an electric motor, the lock mechanism being adjustable between a lock condition and a release condition on operation of the electric motor whereby the keeper is inhibited from moving from the closed position when the lock mechanism is in the lock condition, the lock mechanism including a first detent member and a second detent member that are both movable relative to each other between a first position and a second position, the first detent member and the second detent member adopt the first position when the keeper is in the closed position, and the lock mechanism inhibits the first detent and the second detent from moving from the first position towards the second position when the lock mechanism is in the lock condition.

[0018] The electric strike preferably includes a power storage device within the housing which supplies power to at least the power actuator. It is further preferred that the electric strike include a controller within the housing which in use is adapted for connection to an external power supply, the controller monitors a supply of power from the external power supply to the power storage device, wherein the controller is operable in a fail-safe mode whereby in a power failure event supply of failure to provide power from the external power supply to the power storage device the power storage device provides power to the controller so as to adjust the condition of the lock mechanism to the release condition, or in a fail secure mode whereby in the power failure event the power storage device provides power to the controller so as to adjust the condition of the lock mechanism to the locked condition provided the keeper is in the closed position. The controller preferably includes a switch which is adjustable from outside the housing for adjusting the mode of operating the controller between the fail safe mode and the fail secure mode.

[0019] The electric strike preferably is configured so that the first detent member is movable relative to the second detent member from the first position to a second position when the lock mechanism is in the release condition and the keeper moves between the closed positon and the open position. Furthermore it is preferred that the powered actuator is of the kind that includes an output shaft that rotates about an actuator axis on operation of the electric motor, and a gearbox acting between the electric motor and the output shaft.

[0020] It is preferred that the housing of the electric strike has a longitudinal dimension of no more than 86mm.

[0021 ] It will be convenient to hereinafter describe the invention by reference to the attached illustrations which show a preferred embodiment of an electric strike according to the invention. The particularity of the drawings, and related detailed description is not intended to limit the generality of the previous broad definition of the invention.

[0022] Figure 1 illustrates in diagrammatic form a cross section of an electric strike according to the preferred embodiment of the invention when installed in a door jam in combination with a door latch assembly.

[0023] Figure 2 is an isometric view of the preferred embodiment of the electric strike with the keeper in a closed position. [0024] Figure 3 is an isometric view of the electric strike from Figure 2 with the keeper moved to the open position.

[0025] Figure 4 is an exploded isometric view of the electric strike from Figure 2.

[0026] Figure 5 is an isometric view of the electric strike with the capping removed to reveal the lock mechanism in a lock condition.

[0027] Figure 6 is an isometric sectional view of the electric strike from Figure 5.

[0028] Figure 7 is an isometric view of the electric strike with the capping removed, and the abutment adjusted to an inactive condition.

[0029] Figure 8 is an isometric view of the electric strike from Figure 7 whereby the articulated member has been adjusted to a retracted condition.

[0030] Figure 9 is an isometric staggered sectional view of the electric strike in the condition as illustrated in Figure 8.

[0031 ] Figure 10 is a detail view of the controller from figure 4 with a wiring loom for power and signals added.

[0032] Figure 11 is a reverse view of the controller from figure 10.

[0033] Figure 1 shows in diagrammatic form a cross section of an electric strike assembly 1 mounted to a door frame 2, with a door latch assembly 3 mounted to an edge of adjacent door 4. The door latch assembly 3 includes a latchbolt 5 which is biased towards the extended position as illustrated under the influence of a biasing means (not shown) in a manner that will be understood by those persons skilled in the art. This arrangement allows the door 4 to return from an open position to a closed position without having to operate the electric strike 1. The specific configuration of the door latch assembly 3 is not essential to the invention.

[0034] The electric strike assembly 1 includes a keeper 6 which is shown in Figure 1 in a closed position. The electric strike assembly 1 also includes a lock mechanism formed by a number of elements that will be described in greater detail by reference to later illustrations. The lock mechanism is adjustable between a lock condition and a release condition, whereby the keeper 6 is inhibited from moving from the closed positioned as illustrated in figure 1 when the lock mechanism is in the lock condition. When the keeper 6 is held in the closed position it retains the bolt 5 and therefore prevents the door 4 from being moved relative to the door frame 2. Figure 2 illustrates the electric strike assembly 1 in isolation from the door jam and it can be appreciated that it includes a housing assembly 7 enclosing the keeper 6. Figure 3 illustrates the keeper 6 having been moved to an open position which is achieved by the user pushing the door 4 from the closed position illustrated in Figure 1 to an open position. Once the door 4 has moved from the closed position the keeper 6 will automatically return to the closed position illustrated in Figure 2 under the influence of a biasing spring 8 illustrated in Figure 3.

[0035] It can be appreciated from Figure 4 that the housing assembly 7 is formed by the combination of a base 9 with a capping 10 attachable to one side of the base 9 by a pair of screws 11. A faceplate 12 is attached to the opposed side of the base with another pair of screws 13. While a cover 14 is attached to a front of the base 9 by a pair of pins 15 which locate within bores (not shown) within the front of the base 9. The cover 14 is preferably formed from a cast metal to, whilst the capping 10 is preferably formed from a folded stainless steel and the face plate 12 preferably formed from a stainless steel. The use of the pins 15 in concealed bores to hold the cover 14, and the face plate of stainless steel are included to inhibit an attack on features within the housing assembly 7.

[0036] The base 9 is formed with a first keeper mount 16 which is spaced from a second keeper mount 17, and each include an aligned aperture (obscured), therein to accommodate a shaft 18. The keeper 6 includes a body portion 19 which is engaged by the latchbolt illustrated in Figure 4 when in use (see Figure 1 ). Each of the arm portions 20, 21 includes an aperture 22 therein (only one of which is visible in Figure 4) for accommodating the shaft 18 when the keeper 6 is attached to the base 9. A torsion spring 23 is positioned adjacent the body portion 19, and locates around the shaft 18 when assembled. The torsion spring 23 acts between the keeper 6 and the base 9 to bias the keeper 6 towards a closed positon, which will be explained in greater detail with reference to latter illustrations.

[0037] The electric strike 1 also includes a latchbolt sensor for sensing when the latchbolt 5 engages the electric strike. The latchbolt sensor illustrated includes a probe 24 that extends through an aperture 25 in the base 9 (see also Figure 2). The probe 24 is urged towards an extended position under the influence of a compression spring 26 which acts between the probe 24 and a rear surface of a guide formation 27. The guide formation 27 is held in position relative to the base by a screw 28. The probe interacts with a microswitch 29 (see figure 10) forming part of a controller 30. The adjustment in the condition of the microswitch 29 will be monitored by a microprocessor 31 which also forms part of the controller 30.

[0038] The electric strike 1 according to the invention includes a lock mechanism including a powered actuator 32. The preferred form of powered actuator includes an electric motor 33 that drives a drive shaft 34, through a gearbox 35, in either a clockwise direction or counter clockwise direction. The gearbox 35 may have any suitable gearing ratio, and a ratio of 10 to 1 has been found to be suitable. The powered actuator 32 also includes a shuttle 36 which has a threaded aperture 83 to receive the drive shaft 34. The shuttle 36 can be accommodated by the base 9 so that rotation of the drive shaft 34 in either the clockwise or counter clockwise direction causes the shuttle 36 to move linearly within the housing 7 relative to the motor 33. The movement of the shuttle 36 within the base 9 will be described further by reference to latter illustrations.

[0039] The lock mechanism also includes a first detent member 37 and a second detent member 38 which are movable relative to each other along a detent axis X-X. Each of the first detent 37 and second detent 38 are substantially bullet shaped with a cylindrical outer surface for location within respective first bore and second bore formed in a first detent mount 41 and second detent mount 42 of the base 9 respectively. Each of the first detent 37 and second detent 38 also include a rounded, or more preferably a frusto- conical leading end, which are each configured to interact with a complementary shaped first recess 43 and second recess 44 (see Figure 9) formed in each of the first arm portion 20 and second arm portion 21 of the keeper 6. This complementary interaction of the first detent 37 and second detent 38 with the first arm portion and the second arm portion will be described in greater detail with reference to latter illustrations.

[0040] Figure 4 illustrates each of the first detent 37 and second detent 38 include a trailing end having a substantially planar surface which extends perpendicular to the detent axis X-X (see also Figure 6). The trailing end of each of the first detent 37 and second detent 38 engage an articulated member 45. The articulated member 45 illustrated in Figure 4 includes a first part 46 formed with an aperture 48, and a second part 47 formed with a pin 49 to locate in the aperture 48 of the first part. When the articulated member 45 is assembled it pivots about the pin axis Y-Y so as to move on movement with the first detent 37 and second detent 38 relative to the first mount 41 and second mount 42 respectively.

[0041 ] It is preferred that the first detent 37 and second detent 38 be biased towards a second position (see Figure 8). The preferred arrangement illustrated in Figure 4 involves a detent biasing member 50 in the form of a torsion spring which acts indirectly on the first detent 37 and second detent 38 via the articulated member 45. Clearly other arrangements for biasing the first detent 37 and second detent 30 are possible.

[0042] The guide formation 27 is formed to guide movement of the first part 46 and second part 47 of the articulated member 45 as it moves between an extended condition and a retracted condition. The guide formation 27 is formed with a first U-shaped channel 51 , and a second U-shaped channel 52 each extending inwardly from opposed ends thereof, and aligned parallel to the detent axis X-X. A third U-shaped channel 53 extends inwardly from a side of the guide formation 27, in a direction generally perpendicular to the detent axis X-X. Referring briefly to Figure 6 which illustrates the first part 46 of the articulated member 45 including a first short shaft 54 extending from an under surface thereof, whilst the second part 47 of the articulated member 45 includes a second short shaft 55. The first short shaft 54 and the second short shaft 55 each locate in the first U-shaped channel 51 and second U-shaped channel 52 respectively. The second part 47 of the articulated member includes a third short shaft 56 (see fig 9) formed beneath the pin 49 which locates within the third U-shaped channel 53 (see fig 4) so as to guide linear movement of the third short shaft 56 in a direction generally perpendicular to the detent axis XX. This relative linear movement of the first short shaft 54 and second short shaft 55 relative to each other will be described further by reference to latter illustrations.

[0043] Figure 4 also illustrates an abutment 57 which is beatable on a stud 58 for pivoting relative thereto about an abutment axis Z-Z. It should be noted that the abutment axis ZZ is parallel to the pin axis Y-Y. A lower fixed end of the stud 58 can be fixed to the base 9, whilst an upper free end of the stud 58 locates within an oblong aperture 59 formed in the shuttle 36. Locating the upper free end of the stud 58 within the oblong aperture 59 limits its ability to be forced to move, for reasons that will be become apparent from later in the specification. The abutment 57 is formed with a radial extending arm 60 having a pin 61 adjacent a distal end thereof for location within a groove 62 formed in the shuttle 36. The abutment 57 is also formed with an abutment surface 82 at a distal end of the radial arm 60 which is configured to interact with the articulated member 45 in a manner that will be described in greater detail by reference to latter illustrations.

[0044] Figure 4 also illustrates a series a signal generator 63 associated with one arm 21 of the keeper 6. The signal generators 63 may be in the form of a magnet or the like to produce a signal that is sensed by a hall sensor 90 (see figure 10) located on the controller 30. The keeper hall sensor 90 can sense the position of the keeper 6 relative to the base 9.

[0045] The electric strike 1 is preferably adjustable in its mode of operation between a fail safe mode and a fail secure mode. It is preferred that the controller 30 include a microswitch 91 for adjusting this mode of operation. A portion of the microswitch 91 (see Figure 5) is accessible through a rectangular opening formed in a rear wall of the base 9 so as to enable the adjustment of the microswitch from outside the base 9. More specifically the adjustment of the mode of operation can occur while the capping 10 is attached to the base 9. Furthermore, given the location of the switch 91 adjustment of the mode of operation is inhibited when the electric strike 1 is installed. The switch 91 may be located elsewhere on the housing 7.

[0046] Figure 4 also illustrates a pair of signal generators 66 associated with the member 64 for interacting with a lock hall sensor 92 (see figure 10) and an unlock hall sensor 93, on the controller 30 to indicate the position of the member 64 relative to the controller 30. The member 64 is attached to the shuttle 36 and thereby the controller monitors whether the abutment 57 is in an active position or an inactive position. While it is preferred that the shuttle 36 be formed from metal, so as to form a serviceable bore 83 therein, it is preferred that the member 64 be formed from plastic so that the signal generators 66 can be snap fitted thereon. A signal generator 65 is also included to interact with a reed switch 95 (see fig 10), to indicate when the shuttle 36, and therefore the abutment 57 is in the active position. A reed switch 95 has the advantage in that it doesn’t draw power from the power supply in order to adjust.

[0047] It is preferred that the electric strike 1 include a power storage device 67 within the housing 7 for providing power to at least the controller 30. The preferred form of power storage device 67 illustrated in Figure 4 is in the form of a super capacitor, however other forms of storage devices 67 are clearly possible such as rechargeable batteries or the like. The power storage device 67 is preferably powered by an external power source (not shown) by connecting the electric strike 1 to a hard wired circuit (not shown) for example when the electric strike 1 is installed. The manner in which the electric strike 1 is connected to the hard wired circuit forms no part of the invention. The controller does include a micro-processor 94 (see figure 10) which is capable of monitoring when power is being supplied from the external power source, and in a power failure event adjust the condition of the lock mechanism, or not adjust the condition of the lock mechanism, depending upon the mode of operation selected. It is to be understood that for the purpose of the specification the lock mechanism includes the features of the first detent 37, second detent 38, articulated member 45 and abutment 57. [0048] Referring now to Figure 5 which illustrates the electric strike 1 substantially assembled, however with the capping 10 removed to reveal the inner workings. The keeper 6 is illustrated in a closed position, being urged to adopt the closed position by the torsion spring 23. Furthermore, Figure 6 illustrates the first detent 37 and second detent 38 in a first position, being urged away from adopting the first position by the articulated member 45 which itself is being urged to adopt a retracted condition by the torsion spring 50. While the articulated member 45 is in the extended condition, the abutment 57 can adopt the active position as illustrated in Figure 5. When the abutment 57 is in the active position the radial arm 60 (obscured) of the abutment 57 positions the abutment surface 82 (obscured) adjacent a short end 68 (see Figure 4) of the second part 47 of the articulated member 45. When the abutment surface 82 is in this position it inhibits movement of the short arm 68, and in turn inhibits the articulated member 45 from pivoting about the pin axis YY. The lock mechanism is considered to be in a lock condition when the abutment 57 is in this active position. It can be appreciated from Figure 5, and to a greater extent from Figure 6 that when the articulated member 45 is in the extended condition, the first detent 37 extends across a first interface between the first mount 41 and the first arm portion 20, while the second detent 38 extends across a second interface between the second mount 42 and the second arm portion 21. While the articulated member 45 is retained in the extended condition by the abutment 57, the keeper 6 is unable to move relative to the housing 7.

[0049] While the lock mechanism is in the lock condition the short arm 68 of the second part 47 is positioned relative to the abutment surface 82 so that urging on the keeper 6 to move from the closed position, will apply only a very small force on the abutment 57 in a direction perpendicular to the abutment axis Z-Z. Furthermore, if excessive force is applied to the keeper 6 to the extent that the force is transferred to the stud 58 via the abutment 57, the upper free end of the stud 58 will be limited in its movement to the space defined by the oblong aperture 59.

[0050] Referring now to Figure 7 which illustrates the abutment 57 having been rotated about the shaft 58 to an inactive position. This is achieved by energisation of the motor 33 to cause the drive shaft 34 to rotate, thereby moving the shuttle 36. When the abutment 57 is in this position it no longer prevents movement of the articulated member 45 from the extended condition. This in turn allows the keeper 6 to pivot relative to the housing 7 to adopt an open position as illustrated in Figure 8, which causes the articulated member 45 to adopt a retracted condition as illustrated. It can be appreciated from Figure 9 that rotation of the keeper 6 moves the recesses 43, 44 in the arm portions 20, 21 to slide over the frusto-conical ends of the first detent 37 and second detent 38. This drives the first detent 37 and second detent 38 away from extending across the first interface between the first mount 41 and the first arm portion 20 and the second interface between the second mount 42 and the second arm portion 21. It should also be appreciated by comparing Figure 9 with Figure 6 that the first short shaft 54 on the first part 46 and second short shaft 55 on the second part 44 of the articulated member slide within the first U-shaped channels 51 and second U-shaped channel 52 when the articulated member 45 moves between the extended condition illustrated in Figure 6, and the retracted condition illustrated in Figure 9. Furthermore, the third short shaft 56 slides within the third U-shaped channel 53 so that the pin axis X-X moves relative to the housing assembly 7, towards the abutment axis Z-Z when the articulated member 45 adjusts between the extended condition and retracted condition. The lock mechanism is considered to be in a release condition when the abutment 57 has adopted the inactive condition.

[0051 ] The abutment surface 82 is angled relative to the short arm 68 so that the abutment surface moves substantially tangentially relative to the short arm 68 when the abutment rotates from the active position to the inactive position. The limits any friction between the abutment surface 82 and the short arm 68. Furthermore when the keeper 6 is urged in a preload situation the first detents 37 and second detent 38 transfers the force to the articulated member 45 in such a way that while the articulated member 45 is in the extended condition only a small percentage of the force is transferred by the short arm 68 to the abutment surface 62. [0052] The housing 7 of the electric strike assembly 1 preferably has a longitudinal dimension of no more than 86mm, a depth of no more than 25mm and or a width of no more than 36mm.

[0053] It ought to be appreciated form the forgoing that the electric strike 1 as herein before described can be relatively compact. The arrangement of the first detent 37 being movable relative to the second detent 38, particularly in combination with the articulated member 45 that reduces in length when adjusting further assists in producing a compact electric strike 1. The utilisation of a micro switch to adjust the mode of operation between fail safe and fail secure simplifies the adjustment process when installing the electric strike and reduces the likelihood that it will be inadvertently adjusted during prolonged operation of the electric strike 1. Still furthermore the utilisation of a super capacitor 67 reduces the peak load requirements on the wiring in the building in which the electric strike is installed, which can be an issue if there are multiple electric strikes installed in series.

[0054] Various alterations and/or additions may be introduced into the electric strike assembly as hereinbefore described without departing from the spirit or ambit of the invention.