WO2007049261A1

WO2007049261A1 - A lock

Info

Publication number: WO2007049261A1
Application number: PCT/IE2006/000120
Authority: WO
Inventors: Antoin John Russell; Adrian Laurence O'sullivan; David Thomas Keating
Original assignee: Antoin John Russell; Adrian Laurence O'sullivan; David Thomas Keating
Priority date: 2005-10-26
Filing date: 2006-10-26
Publication date: 2007-05-03
Also published as: IES20060787A2; GB2445135A; GB0807320D0

Abstract

A lock (1) for a door (3) comprises a housing (5) having a bolt (18) slideable therein between a latched state for engaging a receiver (23) and an unlatched state disengaged from the receiver (23). An electrically powered motor (27) through a rack and pinion drive (28) urges the bolt (18) between the latched and the unlatched state in response to manually inputted signals through button operated switches (40,41). A control circuit (35) in response to a valid remotely transmitted signal also operates the motor (27) for urging the bolt (18) between the latched and the unlatched states. A pair of microswitches (43,44) co-operable with a position cam (47) determines the latched and the unlatched states of the bolt (18). The drive motor (27) is operable in response to an unauthorised attempt to urge the bolt (18) from the latched state for urging the bolt (18) into the latched state until the unauthorised attempt has ceased. The bolt (18) is operable into the latched state on respective opposite sides of the housing (5), so that the lock (1) is suitable for a right-handedly hinged and a left-handedly hinged door.

Description

"A lock"

The present invention relates to a lock, and in particular, though not limited to a lock suitable for mounting on a door for securing the door in a closed state.

Locks for use on a door for securing a door in a closed state are well known. Such locks, particularly those for use on an exterior door of a house or building, typically comprise a housing with a bolt slideaple in the housing between an unlatched state, with the bolt typically located within the housing, and a latched state with a portion of the bolt extending outwardly of the housing for engaging a receiver on an adjacent portion of a door frame onto which the door is hinged. A mechanical mechanism typically is provided for urging the bolt between the latched and the unlatched states. Such mechanical mechanisms are typically manually operable by, for example, a knob, which typically is located on the inside of the door, and a key operated barrel actuator, which typically is located on the outer side of the door. Alternatively, the mechanical mechanism for urging the bolt between the latched and the unlatched states may be operable directly by a key. It is also known to provide electrically powered drive mechanisms for driving the bolt between the latched and the unlatched states, which may comprise electrical motors, solenoids or the like. However, in general, such locks suffer from a number of disadvantages. For example, where a lock comprises an electrically powered drive mechanism for urging the bolt between the latched and the unlatched states, in many cases, it is difficult to provide a manual mechanism which can be operated to override the electrically powered drive mechanism. Another problem with such known locks is that in general they are suitable only for use with a particular type of door, for example, in general, each lock is suitable for use on only one of a right-handedly , hinged or a left-handedly hinged door, and thus, it is necessary to carry stocks of two different types of locks, one type which is suitable for mounting on a right-handedly hinged door, and the other type which is suitable for mounting on a left-handedly hinged door.

Additionally, such locks with electrically powered drive mechanisms tend to be relatively complex, and in particular, the drive mechanisms of such locks tend to be relatively complex, thus adding to the subsequent maintenance required in order to keep such locks in operation, and additionally, contributing to the cost of the locks.

There is therefore a need for a lock which addresses at least some of the problems of prior art locks.

The present invention is directed towards providing such a lock.

According to the invention there is provided a lock comprising a housing, a bolt slideable in the housing between a latched state for engaging an external receiver and an unlatched state disengaged from the receiver, a monitoring means for monitoring the state of the bolt, and a drive means for urging the bolt between the latched and the unlatched state, the drive means being responsive to the monitoring means detecting movement of the bolt from the latched state for urging the bolt into the latched state.

In one embodiment of the invention a transmission means is provided for transmitting drive from the drive means to the bolt. Preferably, the transmission means comprises a slipping clutch, for facilitating operation of the drive means when the bolt is in one of the latched and the unlatched states.

In one embodiment of the invention the drive transmission means comprises a rack and pinion transmission means. Preferably, the rack and pinion transmission means comprises the pinion driven by the drive means, which in turn drives a rack of the rack and pinion transmission means for driving the bolt. Advantageously, the rack is mounted on the bolt. Ideally, the pinion is driven by the drive means through the slipping clutch.

In another embodiment of the invention the pinion is rotatably mounted on a drive shaft of the drive means, and the slipping clutch is mounted on the drive shaft of the drive means for driving the pinion. In a further embodiment of the invention the slipping clutch is configured not to slip until a force acting on the bolt is of value greater than the value of a force which could be applied to the bolt during an unauthorised attempt to urge the bolt from the latched state.

Preferably, the clutch is configured not to slip until the force acting on the bolt is of value greater than the value of a force which could be exerted on the bolt during an unauthorised attempt to urge the bolt from the latched state by inserting a credit card, blade or other such resilient element between a door on which the lock is mounted and an adjacent portion of a door frame.

In one embodiment of the invention the drive means comprises a drive motor. Preferably, the drive motor comprises an electrically powered drive motor.

In another embodiment of the invention the monitoring means comprises a first sensor for determining when the bolt is in the latched state. Preferably, the monitoring means comprises a second sensor for determining when the bolt is in the unlatched state. Advantageously, each one of the first and second sensors is provided by a microswitch.

In one embodiment of the invention each microswitch comprises an actuating arm, a cam follower carried on the actuating arm for engagement with a position cam when the bolt is in the corresponding one of the latched and the unlatched states.

In another embodiment of the invention a control means is provided for controlling the operation of the drive means, the control means being responsive to the monitoring means. Preferably, the control means comprises a control circuit. Advantageously, the control circuit comprises a microprocessor, the microprocessor being programmed to read signals from the monitoring means.

In one embodiment of the invention a receiving means is provided for receiving a transmitted signal, and the control means is responsive to the received transmitted signal for operating the drive means to urge the bolt into one of the latched and the unlatched state. Preferably, the receiver is a radio receiver.

In another embodiment of the invention a transmitter is provided for transmitting a signal indicative of the state of the bolt. Preferably, the transmitter is a radio transmitter.

In another embodiment of the invention the microprocessor is programmable to operate as a master microprocessor for controlling microprocessors of one or more other locks in which the microprocessor of the one or more other locks are programmed to operate as slave microprocessors.

Preferably, the microprocessor of the lock configured as a master microprocessor operates the transmitter for transmitting appropriately encoded signals for reception by the other locks for operation thereof.

In another embodiment of the invention the control means comprises an input means for facilitating manual inputting of a signal to the lock for operating the bolt between the latched and the unlatched state. Preferably, the input means comprises at least one manually operable input switch for operating the bolt into one of the latched and the unlatched state. Advantageously, the input means comprises a pair of manually operable input switches, one of the manually operable input switches being provided for operating the drive means to urge the bolt into the latched state, and the other of the manually operable input switches being provided for operating the drive means for urging the bolt into the unlatched state.

In one embodiment of the invention a first override means is provided for overriding the drive means for facilitating urging the bolt into at least one of the latched and the unlatched states independently of the drive means. Preferably, the first override means is adapted for urging the bolt between the latched and the unlatched state. Advantageously, the first override means comprises a key operated barrel actuator.

Ideally, the key operated barrel actuator is co-operable with the drive transmission means for urging the bolt between the latched and the unlatched state.

In another embodiment of the invention a second override means is provided for overriding the drive means for facilitating urging of the bolt into at least one of the latched and the unlatched states independently of the drive means. Preferably, the second override means comprises a knob mounted on the bolt.

In another embodiment of the invention the slipping clutch is configured to slip when the force on the bolt is greater than the force which could be applied to the bolt during an unauthorised attempt to urge the bolt from the latched state, but is configured to slip at a force which is not so great as to prevent the bolt being urged from the latched state by one of the first and second override means.

Preferably, a portion of the bolt is urgeable from the housing on one side thereof when the bolt is in the latched state for engaging the external receiver.

Advantageously, respective portions of the bolt are alternately urgeable outwardly of the housing on respective opposite sides thereof into respective latched states so that the lock is suitable for mounting on a right-handedly hinged or a left-handedly hinged closure.

In another embodiment of the invention the bolt is an elongated bolt, and the respective portions which are alternately urgeable outwardly of the housing on the respective opposite sides thereof are formed by respective opposite end portions of the bolt.

In a further embodiment of the invention an opening is provided in respective opposite sides of the housing for accommodating the bolt therethrough on the respective opposite sides thereof. In another embodiment of the invention the device means is responsive to a signal indicative of a door with which the lock is associated being in a closed state for urging the bolt into the latched state.

The invention also provides in combination the lock according to the invention, and a discrete handheld transmitter a discrete handheld transmitter for transmitting appropriately encoded signals for reception by the radio receiver of the lock for operating the bolt thereof into one of the latched and the unlatched states.

Additionally the invention provides a combination of a plurality of the locks according to the invention in which the microprocessor of one of the locks is configured as a master microprocessor, and the microprocessors of the other locks are configured as slave microprocessors, so that the locks, the microprocessors of which have been configured as slave microprocessors are operable for urging the respective bolts thereof into one of the latched and the unlatched states in response to a signal from the lock, the microprocessor of which is configured as a master microprocessor.

The advantages of the invention are many. The lock according to the invention is a relatively uncomplex lock, and thus, can be provided at a relatively low cost, and is relatively maintenance free. Another advantage of the lock according to the invention is that it can be provided with one or more override means for facilitating overriding the drive means of the lock for operating the bolt of the lock into at least one of the latched and the unlatched states, so that the lock can be operated in the event of a power failure or a low battery. A particularly important advantage of the invention is achieved when the lock comprises a transmission means which includes a slipping clutch, and in particular, when the slipping clutch is configured not to slip until a force acting on the bolt is of value greater than the value of a force which could be applied to the bolt in the event of an unauthorised attempt to urge the bolt from the latched state, for example, by a credit card, a blade or other such resilient element, while at the same time the clutch is configured to slip when the force applied to the bolt is greater than that which could be applied to the bolt during an unauthorised attempt to urge the bolt from the latched state, but which is not so great as to prevent operation of the bolt by either or both override means.

Another advantage of the invention is that by virtue of the fact that the lock is a relatively uncomplex lock, as well as it being produceable at a relatively low cost, the subsequent maintenance in order to keep the lock operational is minimal, and in general, virtually no subsequent maintenance is required.

A particularly important advantage of the invention is achieved when the bolt is adapted to be urgeable outwardly of the housing on respective opposite sides thereof into respective latched states, since this permits the lock to be used on either left-handedly hinged or right-handedly hinged doors without any modification or adaptation of the lock. Thus, the volume of stocks which would have to be carried in order to satisfy the demand for locks for both right-handedly hinged and left- handedly hinged doors is effectively halved.

The invention will be more clearly understood from the following description of an embodiment thereof, which is given by way of example only, with reference to the accompanying drawings in which:

Fig. 1 is a perspective view of a lock according to the invention,

Fig. 2 is a front elevational view of the lock of Fig. 1 ,

Fig. 3 is a rear elevational view of the lock of Fig. 1 ,

Fig. 4 is a side elevational view of the lock of Fig. 1 ,

Fig. 5 is a front elevational view of the lock of Fig. 1 with a portion of the lock removed,

Fig. 6 is a view similar to Fig. 5 of the lock of Fig. 1 with a portion of the lock in a different position,

Fig. 7 is a block representation of circuitry of the lock of Fig. 1 ,

Fig. 8 is a perspective view of a detail of the lock of Fig. 1 ,

Fig. 9 is a block representation of a typical operation of the lock of Fig. 1 in conjunction with a plurality of locks,

Fig. 10 is a front elevational view of a lock according to another embodiment of the invention,

Fig. 11 is a rear elevational view of the lock of Fig. 10,

Fig. 12 is a front elevational view of the lock of Fig. 10 with a substantial portion of the lock removed,

Fig. 13 is a side elevational view of the portion of Fig. 12 of the lock of Fig. 10,

Fig. 14 is a perspective view of the portion of Fig. 12 of the lock of Fig. 10, and

Fig. 15 is another perspective view of a part of the portion of Fig. 12 of the lock of Fig. 10.

Referring to the drawings and initially to Figs. 1 to 9 thereof, there is illustrated a lock according to the invention indicated generally by the reference numeral 1. The lock 1 is particularly suitable for securing a door, and in particular, an exterior door 3 of a building (not shown) in a door frame 4. A portion of the door 3 and the door frame 4 only are illustrated in Figs. 5 and 6. The lock 1 is also suitable for securing a window, or any other closure in a closed state within a frame. The lock 1 comprises a housing 5 having a back plate 6 and a cover 2, which together define a hollow interior region 14. The cover 2 comprises a front plate 11 , a pair of spaced apart side walls 7 and 8 extending from the front plate 11 , and spaced apart top and bottom end walls 9 and 10 extending from the front plate 11 joining the side walls 7 and 8. The cover 2 is secured to the base plate 6 by screws 12. Six holes 15 extending through the back plate 6 accommodate screws (not shown) for securing the back plate 6, and in turn the lock 1 to an inside major surface 16 of the door 3.

A bolt 18 is slideably carried in a pair of bearing members 19 which are located in the hollow interior region 14 and secured to the back plate 6 at respective opposite sides thereof. The bolt 18 is slideable in the bearing members 19 between a latched state illustrated in Fig. 6 with a portion 20 of the bolt 18 extending outwardly of the housing 5 through an opening 21 in the side wall 8 with the portion 20 of the bolt 18 engaging a receiver 23 secured to the door frame 4, and an unlatched state illustrated in Fig. 5 with the bolt 18 disengaged from the receiver 23. A recess 24 in the receiver 23 is provided for receiving the portion 20 of the bolt 18 therein when the bolt 18 is in the latched state. A pair of holes extending through the receiver 23 accommodate screws (not shown) for securing the receiver 23 to the door frame 4.

A drive means comprising an electrically powered gear drive motor 27 is mounted in the hollow interior region 14 on the back plate 6 for urging the bolt 18 between the latched state and the unlatched state. A first drive transmission means, namely, a first drive transmission 26 transmits drive from the drive motor 27 to the bolt 18. The first drive transmission 26 comprises a rack and pinion transmission 28 which comprises a pinion 29 engageabie with a rack 32 on the bolt 18 for driving thereof. The pinion 29 is rotatably mounted on a drive shaft 30 of the drive motor 27 and is driven by the drive shaft 30 through a slipping clutch 31 by the drive motor 27, for transmitting drive from the drive motor 27 to the rack 32 and in turn to the bolt 18 for urging the bolt 18 between the latched and the unlatched state.

A control means, in this embodiment of the invention an electronic control circuit, which is illustrated in block representation in Figs. 5 to 7, is located in the hollow interior region 14, and comprises a microprocessor 36 for controlling the operation of the drive motor 27 for urging the bolt 18 between the latched and the unlatched states. The control circuit 35 is responsive to a pair of button actuated switches 38 and 39 which are located in the hollow interior region 14 for operating the drive motor 27 to urge the bolt 18 into the latched and the unlatched states, respectively. Buttons 40 and 41 extending through the front plate 11 facilitate operation of the button switches 38 and 39. A battery 42 is located within the hollow interior region 14 for powering the control circuit 35, the microprocessor 36 and the drive motor 27.

A monitoring means comprising a pair of microswitches, namely, a first microswitch 43 and a second microswitch 44 located within the hollow interior region 14 are provided for monitoring the state of the bolt 18 and for determining when the bolt 18 is being urged from the latched state. An actuating arm 45 extending from the first microswitch 43 carries a cam follower 46 which is engageable with a camming means, namely, a position cam 47 mounted on the bolt 18 when the bolt 18 is in the latched state. A plunger 48 extending from the microswitch 43 is depressed into the microswitch 43 by the actuating arm 45 on engagement of the cam follower 46 with the position cam 47 for closing a switch (not shown) in the microswitch 43, for in turn indicating that the bolt 18 is in the latched state. An actuating arm 49 extending from the second microswitch 44 carries a cam follower 50 which is engageable with the position cam 47 when the bolt 18 is in the unlatched state. A plunger 52 extending from the microswitch 44 is depressed into the microswitch 44 by the actuating arm 49 when the cam follower 50 engages the position cam 47 for closing a switch (not shown) in the microswitch 44, for in turn indicating the unlatched state of the bolt 18.

Signals from the microswitches 43 and 44 are read by the microprocessor 36 for determining the state of the bolt 18, and also for determining if an unauthorised attempt is being made to urge the bolt 18 from the latched state. On an unauthorised attempt being made to urge the bolt 18 from the latched state, the microprocessor 36 operates the control circuit 35, to in turn operate the drive motor 27 for urging the bolt 18 back into the latched state. While an unauthorised attempt is being made to urge the bolt 18 from the latched state, each time the bolt is urged from the latched state, the drive motor 27 is activated for returning the bolt 18 to the latched state, and since the drive motor 27 drives the pinion 29 through the slipping clutch 31 , there is no danger of the drive motor 27 being burnt out. Thus, the drive motor 27 effectively acts as an electronic spring for retaining the bolt 18 in the latched state. However, due to the fact that the drive motor 27 is only operated by the control circuit 35 in response to the first microswitch 43 indicating that an unauthorised attempt is being made to urge the bolt 18 from the latched to the unlatched state, the drive motor 27 does not have to be continuously powered for maintaining the bolt 18 in the latched state, rather, the drive motor 27 is only operated for urging the bolt between the latched and the unlatched state and for returning the bolt 18 to the latched state in the event of an unauthorised attempt being made to urge the bolt 18 from the latched state. Accordingly, the power demand from the battery 42 is minimised, thereby facilitating the maximisation of the life of the battery 42.

A second transmission means comprising a transmission element 55, see Fig. 8, is located in the hollow interior region 14 for facilitating coupling a key operated barrel actuator 56 to the bolt 18, so that the key operated barrel actuator acts as a first override means for overriding the drive motor 27 for permitting manual urging of the bolt 18 between the latched and the unlatched states. The transmission element 55 is rigidly mounted on the drive shaft 30 of the drive motor 27. A socket 58 in the transmission element 55 is engageable with a blade member 59 extending from the key operated barrel actuator 56. Typically, the key operated barrel actuator 56 would be mounted on an outer major surface (not shown) of the door 3 for facilitating manually operating the lock 1 from the exterior of the building. Pins 60 located at 180° relative to each other around the socket 58 engage the blade 59, and permit approximately 150° of relative movement between the transmission element 55 and the blade member 59 for facilitating movement of the bolt 18 between the latched and the unlatched state by the drive motor 27 independently of the key operated barrel actuator 56, while at the same time facilitating manual urging of the bolt 18 between the latched and the unlatched state by the key operated barrel actuator 56 independently of the drive motor 27. In this embodiment of the invention the bolt 18 is of length to be operable alternately into respective latched states on respective opposite sides of the housing 5, so that the lock 1 without any modification is suitable for use on both a right-handedly hinged door and a left-handedly hinged door. An opening (not shown) in the side wall 7 accommodates a portion 63 of the bolt 18 to extend outwardly of the housing 5 into a latched state for engaging a receiver similar to the receiver 23 on the opposite side of the lock mounted on a door frame 3 when the lock is used on a right-handedly hinged door. The receiver 23 illustrated in Figs. 5 and 6 mounted on the door frame 4 is located for using the lock 1 on a left-handedly hinged door. Thus, when the bolt 18 is in the unlatched state when mounted on a door as illustrated in Figs. 5 and 6, the portion 63 of the bolt 18 is actually in the latched state for engaging a receiver on the opposite side of the lock 1, and vice versa.

A second override means for overriding the drive motor 27 comprises a knob 64 which is selectively securable to either end of the bolt 18 by a screw 65 which engages either one of a threaded bore 66 or 67 extending axially into the bolt 18 from respective opposite ends thereof. Thus, depending on which handed door the lock 1 is mounted, the knob 64 is secured to the end thereof which does not engage the receiver 23 when the bolt 18 is in the latched state. The knob 64 facilitates manual operation of the bolt 18 between the latched and the unlatched state independently of the drive motor 27, and also independently of the key operated barrel actuator 56.

The slipping clutch 31 is set to slip not until a reasonable amount of force is applied to the bolt 18 for urging the bolt from the latched to the unlatched state. In other words, the slipping clutch is set to slip when the bolt 18 is being manually urged from the latched state to the unlatched state by either the override knob 64 or the key operated barrel actuator 56. However, the slipping clutch 31 is set not to slip until the amount of force applied to the bolt 18 is greater than the force which could be applied to the bolt 18 by an unauthorised attempt to urge the bolt 18 from the latched state, for example, the amount of force which could be applied by an attempt to urge the bolt from the latched state by inserting a credit card or other such resilient element between the bolt and the receiver or by other such unauthorised attempts. Thus, in order to urge the bolt manually by the override knob 64 or by the key operated barrel actuator 56, a reasonable amount of force is required, and that amount of force would be greater than that which could be applied during a typical unauthorised attempt to urge the bolt 18 from the latched state.

A receiving means, namely, a radio receiver 70 is located in the hollow interior region 18 for receiving remotely generated radio signals for operating the lock 1 between the latched and the unlatched state. The microprocessor 36 reads signals received by the radio receiver 70, and is responsive to a validly received radio signal for operating the drive motor 27 to urge the bolt 18 into the latched or the unlatched state, depending on an instruction encoded in the received valid radio signal.

A handheld portable radio transmitter/receiver unit 71 is provided for remotely transmitting signals to the radio receiver 70 in the lock 1 for remotely operating the bolt 18 between the latched and the unlatched states. Two button operated switches 74 and 75 are provided on the handheld transmitter/receiver unit 71 for operating the handheld transmitter/receiver unit 71 to output the appropriate one of the encoded signals for operating the lock to urge the bolt 18 into the desired one of the latched and the unlatched state. Activation of the switch 74 operates the handheld transmitter/receiver unit 71 for outputting the encoded signal for operating the lock 1 to urge the bolt 18 into the latched state, while activation of the switch 75 operates the handheld transmitter/receiver unit 71 to output the encoded signal for operating the bolt 18 into the unlatched state. Two light emitting diodes 76 and 77 on the handheld transmitter/receiver unit 71 indicate the latched and unlatched states, respectively, of the bolt 18 of the lock 1 in response to signals received from a transmitter 72 of the lock 1. The radio transmitter 72 also located in the hollow interior region 14 of the lock 1 is operated under the control of the microprocessor 36 to transmit data indicative of the latched and unlatched states of the bolt 18.

Additionally, in this embodiment of the invention the microprocessor 35 is programmed so that the lock 1 may act as a master lock 1. This, thus, enables the lock 1 to interact and communicate with other locks 1a and 1b, similar to the lock 1 on other doors of a building, the microprocessors of which are programmed to act as slave microprocessors, and in turn the locks 1a and 1b are slave locks. For example, if a user desired to lock all the doors of a building, the user would transmit an appropriately encoded instruction signal from the handheld transmitter/receiver unit 71 , which on receipt by the radio receiver 70 of the lock 1 and being read by the microprocessor 36, the microprocessor 36 would operate the control circuit 35 to in turn operate the drive motor 27 to urge the bolt 18 into the latched state, and would simultaneously transmit an appropriately encoded signal through the transmitter 72 for reception by the other similar locks 1a and 1 b in the building, which would cause the microprocessors of the other locks 1a and 1 b in the building to operate their respective control circuits for in turn operating the respective drive motors for urging the corresponding bolts into the latched state. This, thus, would allow the lock 1 to operate as a master lock along with a plurality of slave locks 1 a and 1 b. Additionally, on the slave locks 1a and 1b having been operated to urge their corresponding bolts 18 into the latched state, the microprocessors of the slave locks are programmed to transmit a signal for reception by the master lock 1 indicative of the latched and unlatched state of their respective bolts 18. The microprocessor 36 of the lock 1 , which is programmed to be the master microprocessor on receiving the signals indicative of the states of the slave locks 1a and 1b operates the transmitter 72 for outputting a signal indicative of the states of all the locks for reception by the handheld transmitter/receiver unit 71, which in turn indicates the status of the locks by powering the appropriate one of the light emitting diodes 76 and 77.

Similarly, an appropriately encoded signal would be transmitted by the handheld transmitter/receiver unit 71 for reception by the lock 1 to which the microprocessor 36 would be responsive for operating the control circuit 35 for in turn operating the drive motor 27 for urging the bolt 18 into the unlatched state, and for similarly operating the slave locks.

In use, the lock 1 is secured to the door 3 and the receiver 23 is secured to the door frame 4. The key operated barrel actuator 56 is then secured to the outer surface of the door 3 with the blade member 59 engaged in the socket 58 of the transmission element 55. Depending on whether the lock is being secured to a right-handed or left-handed door, the knob 64 is secured to the appropriate end of the bolt 18 by the screw 65 in the appropriate one of the threaded bores 66 or 67. With the lock 1 so secured to the door 3, the lock 1 is ready for use. The lock 1 may be used on its own on a single door, or it may be used in conjunction with a plurality of similar locks in which the respective microprocessors 37 have been programmed so that the other locks, for example, the locks 1 a and 1 b, act as slave locks on other doors of the building. If the lock 1 is to operate on its own as a single lock, to operate the lock 1 for urging the bolt 18 into the latched or the unlatched state, the handheld transmitter/receiver unit 71 is operated for outputting an appropriately encoded latch or unlatch signal. On reception of the encoded latch or unlatch signal by the radio receiver 70 of the lock 1 , the microprocessor 36 operates the control circuit 35 for in turn operating the drive motor 27 for urging the bolt 18 into the appropriate one of the latched and the unlatched states. On the other hand, if a person at the inside of the door 3 wishes to operate the lock into the latched or the unlatched state, the appropriate one of the buttons 40 and 41 of the button operated switches 38 and 39 is depressed. Alternatively, if a person at the inside of the door 3 wishes to manually operate the lock 1 , the knob 64 is gripped and urged in the appropriate direction for urging the bolt 18 into the desired one of the latched and the unlatched state. If, on the other hand, the person wishes to manually operate the lock from outside the door, a key is inserted in the key operated barrel actuator 56, which is then operated in the appropriate manner for urging the bolt 18 into the desired one of the latched and the unlatched state.

If the door is closed and the bolt 18 of the lock 1 is in the latched state, and an unauthorised attempt is made to urge the bolt 18 from the latched state, by, for example, an intruder using a credit card, a blade or other such thin resilient element, the microprocessor 36 on detecting a signal from the microswitch 43 indicative of the bolt 18 being urged from the latched state, operates the control circuit 35 for in turn operating the drive motor 27 for urging the bolt 18 into the latched state. The control circuit 35 continues to operate the drive motor 27 for urging the bolt 18 into the latched state each time a signal from the microswitch 43 is indicative of the bolt 18 being urged from the latched state, for so long as the unauthorised attempt to urge the bolt from the latched state continues. During this period while the drive motor 27 is being operated for urging the bolt into the latched state, the slipping clutch 31 continues to slip for so long as the bolt 18 remains in the latched state, thereby avoiding any danger of the drive motor 27 burning out. On the unauthorised attempt to urge the bolt from the latched state ceasing and the signals from the microswitch 43 are indicative of the bolt 18 being in the latched state, the drive motor 27 is deactivated by the electronic control circuit 35, and the bolt 18 remains in the latched state until it is subsequently urged from the latched to the unlatched state as a result of a transmission from the handheld transmitter/receiver 71 or the button operated switches 38 and 39, or by the knob 64 or the key operated barrel actuator 56.

Where the lock 1 is to operate as a master lock in combination with a plurality of other slave locks similar to the lock 1 on other doors, and where the microprocessors of the other locks are programmed to act as slave microprocessors, on receipt of the appropriately encoded signal from the handheld transmitter/receiver unit 71, the microprocessor 36 of the lock 1 operates the control circuit 35 thereof for in turn operating the drive motor 27 to urge the bolt 18 into the appropriate one of the latched or the unlatched states. The microprocessor 36 simultaneously outputs an appropriately encoded signal to the other locks, and on reception of the signal by the microprocessors of the other locks, the microprocessor of the other locks operates the respective corresponding control circuits for in turn operating the corresponding drive motors for urging the corresponding bolts of the other locks into the appropriate one of the latched and the unlatched states.

Referring now to Figs. 10 to 15 there is illustrated a lock according to another embodiment of the invention indicated generally by the reference numeral 80. The lock 80 is substantially similar to the lock 1 of Figs. 1 to 9, and similar components are identified by the same reference numerals. Although not illustrated in Figs. 12 to 15, the lock 80 includes the drive motor 27, the rack and pinion transmission 28, and the rack 32 of the rack and pinion transmission 28 is formed on the bolt 18 of the lock 80 in similar fashion as the rack 32 is formed on the bolt 18 of the lock 1. Furthermore, the lock 80 includes the electronic control circuit 35 and the microprocessor 36 as well as all the associated components of both the drive motor 27, the rack and pinion transmission 28 and the control circuit 35 as already described with reference to the lock 1.

The main difference between the lock 80 and the lock 1 is in the arrangement of the first override means. In this embodiment of the invention the first override means which comprises a latch 81 which is pivotally mounted in the back plate 6, and which is operable by the blade member 59 of the key operated barrel actuator 56 is only suitable for operating the bolt 18 from the latched state to the unlatched state. Additionally, the latch 81 is not coupled to or mounted on the drive shaft 30 of the drive motor 27. In this embodiment of the invention the latch 81 is mounted on a disc 83 which is pivotal in the back plate 6, and is provided with a slot 84 for engaging the blade member 59 of the key operated barrel actuator 56. The latch 81 is engageable with a pin 82 extending through and from the bolt 18 so that when the latch 81 is pivoted in the direction of the arrow A, see Figs. 12 and 14, the latch 81 engages the pin 82 and thereby urges the bolt 18 from the latched state to the unlatched state.

In this embodiment of the invention the microprocessor 36 of the control circuit 35 is programmed operate the control circuit 35 for in turn operating the drive motor 27 to return the bolt 18 to the latched state after a predetermined period of time, typically, twenty seconds after it has been urged into the unlatched state by the latch 81. The microprocessor 36 is programmed to determine when the bolt 18 has been urged into the unlatched state by the latch 81 from signals read from the first and second microswitches 43 and 44. The microprocessor 36 is also programmed to read signals from a proximity sensor mounted on the door which outputs a signal indicative of the door being in the closed state in the doorframe, and if the bolt 18 has been urged into the unlatched state by the latch 81 on receiving a signal from the proximity switch indicative of the door being in the closed state, the microprocessor 36 operates the control circuit 35 for in turn operating the drive motor 27 for urging the bolt 18 into the latched state.

Operation of the lock 80 is similar to operation of the lock 1 , with the exception that the bolt 18 can only be operated from the latched to the unlatched state by the key operated barrel actuator 56.

Additionally, the lock 80 is provided with a radio transmitter and receiver similar to that described with reference to the lock 1 , and thus, the lock 80 can be operated by a remotely transmitted signal from a handheld transmitter/receiver unit similar to the handheld transmitter/receiver unit 71 described with reference to the lock 1 of Figs. 1 to 9. Similarly, a plurality of the locks 80 could be provided and the microprocessor of one of the locks 80 could be programmed as a master microprocessor and the microprocessor of the remaining locks 80 may be programmed as slave microprocessors, so that the locks 80 could be arranged in a master slave arrangement similar to that described with reference to the lock 1 of Figs. 1 to 9.

While the locks have been described as being suitable for use in a master/slave arrangement, while this is desirable, it is not essential, and in certain cases, it is envisaged that the locks may be supplied with the microprocessor programmed so that the locks operate as single standalone locks.

It is also envisaged that while it is desirable, it is not essential that the locks should be provided with a transmitter, although the advantage of providing a transmitter is that even when the lock is to operate as a standalone lock, a signal indicative of the latched or unlatched state of the bolt can be transmitted for reception by the handheld transmitter/receiver unit, which would also be provided with a radio receiver to indicate the latched or unlatched state of the bolt.

Additionally, it will be appreciated that where the locks are provided to act as master locks in combination with slave locks, it is not essential that the slave locks be provided with transmitters, although it is desirable, since the slave locks once provided with transmitters can transmit signals indicative of the latched or unlatched status of their respective bolts.

While the locks have been described as being surface mounted on a door, it is envisaged that the locks may be provided in the form of a mortise locks.

Additionally, while the locks have been described as comprising a microprocessor which can be programmed to be either a master microprocessor or a slave microprocessor, and while the lock, the microprocessor of which has been programmed to be a master microprocessor has been described as being responsive to remotely transmitted signals for operating the bolt into the appropriate one of the latched and the unlatched states, and for transmitting signals for operating the bolts of the locks, the microprocessors of which are programmed as slave microprocessors into the corresponding one of the latched and the unlatched states, it will be readily apparent to those skilled in the art that the master microprocessor could also be responsive to an input signal being inputted through the appropriate one of the button actuated switches for operating the bolt into the appropriate one of the latched and the unlatched states, and for simultaneously transmitting signals to locks, the microprocessors of which have been programmed as slave microprocessors for operating the bolts of the slave locks into the corresponding one of the latched and unlatched states.

It is also envisaged that while the locks have been described as being battery powered, the lock may also be powered from a mains power supply, which typically would be stepped down to a low voltage, for example, 5 volts or 10 volts by a suitable transformer.

While the microprocessor 80 has been described as being programmed to be responsive to a proximity sensor on the door, which outputs a signal indicative of the door being in a closed state, for operating the drive motor to return the bolt to the latched state after the bolt has been urged to the unlatched state by the latch 81 , it is envisaged that the microprocessor of the lock 80 may be programmed to operate the drive motor to urge the bolt into the latched state in response to any signal which is indicative of the door being urged into the closed state in the doorframe, irrespective of how the bolt had previously been urged into the unlatched state. Additionally, it is envisaged that the proximity sensor may be located in the lock 80. It will also be appreciated that the microprocessor of the lock 1 described with reference to Figs. 1 to 9 may be similarly programmed to be responsive to a signal which is indicative of the door being in a closed state for operating the drive motor to urge the bolt into the latched state. It will also be appreciated that any suitable means for producing a signal indicative of a door with which the lock is associated being urged into a closed state may be used instead of a proximity sensor.

Claims

1. A lock comprising a housing, a bolt slideable in the housing between a latched state for engaging an external receiver and an unlatched state disengaged from the receiver, a monitoring means for monitoring the state of the bolt, and a drive means for urging the bolt between the latched and the unlatched state, the drive means being responsive to the monitoring means detecting movement of the bolt from the latched state for urging the bolt into the latched state.

2. A lock as claimed in Claim 1 in which a transmission means is provided for transmitting drive from the drive means to the bolt.

3. A lock as claimed in Claim 2 in which the transmission means comprises a slipping clutch, for facilitating operation of the drive means when the bolt is in one of the latched and the unlatched states.

4. A lock as claimed in Claim 2 or 3 in which the drive transmission means comprises a rack and pinion transmission means.

5. A lock as claimed in Claim 4 in which the rack and pinion transmission means comprises the pinion driven by the drive means, which in turn drives a rack of the rack and pinion transmission means for driving the bolt.

6. A lock as claimed in Claim 5 in which the rack is mounted on the bolt.

7. A lock as claimed in Claim 5 or 6 in which the pinion is driven by the drive means through the slipping clutch.

8. A lock as claimed in any of Claims 5 to 7 in which the pinion is rotatably mounted on a drive shaft of the drive means, and the slipping clutch is mounted on the drive shaft of the drive means for driving the pinion.

9. A lock as claimed in any of Claims 3 to 8 in which the slipping clutch is configured not to slip until a force acting on the bolt is of value greater than the value of a force which could be applied to the bolt during an unauthorised attempt to urge the bolt from the latched state.

10. A lock as claimed in Claim 9 in which the clutch is configured not to slip until the force acting on the bolt is of value greater than the value of a force which could be exerted on the bolt during an unauthorised attempt to urge the bolt from the latched state by inserting a credit card, blade or other such resilient element between a door on which the lock is mounted and an adjacent portion of a door frame.

11. A lock as claimed in any preceding claim in which the drive means comprises a drive motor.

12. A lock as claimed in Claim 11 in which the drive motor comprises an electrically powered drive motor.

13. A lock as claimed in any preceding claim in which the monitoring means comprises a first sensor for determining when the bolt is in the latched state.

14. A lock as claimed in any preceding claim in which the monitoring means comprises a second sensor for determining when the bolt is in the unlatched state.

15. A lock as claimed in Claim 13 or 14 in which each one of the first and second sensors is provided by a microswitch.

16. A lock as claimed in Claim 15 in which each microswitch comprises an actuating arm, a cam follower carried on the actuating arm for engagement with a position cam when the bolt is in the corresponding one of the latched and the unlatched states.

17. A lock as claimed in any preceding claim in which a control means is provided for controlling the operation of the drive means, the control means being responsive to the monitoring means.

18. A lock as claimed in Claim 17 in which the control means comprises a control circuit.

19. A lock as claimed in Claim 18 in which the control circuit comprises a microprocessor, the microprocessor being programmed to read signals from the monitoring means.

20. A lock as claimed in any of Claims 17 to 19 in which a receiving means is provided for receiving a transmitted signal, and the control means is responsive to the received transmitted signal for operating the drive means to urge the bolt into one of the latched and the unlatched state.

21. A lock as claimed in Claim 20 in which the receiver is a radio receiver.

22. A lock as claimed in any of Claims 17 to 21 in which a transmitter is provided for transmitting a signal indicative of the state of the bolt.

23. A lock as claimed in Claim 22 in which the transmitter is a radio transmitter.

24. A lock as claimed in any of Claims 19 to 23 in which the microprocessor is programmable to operate as a master microprocessor for controlling microprocessors of one or more other locks in which the microprocessor of the one or more other locks are programmed to operate as slave microprocessors.

25. A lock as claimed in Claim 24 in which the microprocessor of the lock configured as a master microprocessor operates the transmitter for transmitting appropriately encoded signals for reception by the other locks for operation thereof.

26. A lock as claimed in any of Claims 17 to 25 in which the control means comprises an input means for facilitating manual inputting of a signal to the lock for operating the bolt between the latched and the unlatched state.

27. A lock as claimed in Claim 26 in which the input means comprises at least one manually operable input switch for operating the bolt into one of the latched and the unlatched state.

28. A lock as claimed in Claim 26 or 27 in which the input means comprises a pair of manually operable input switches, one of the manually operable input switches being provided for operating the drive means to urge the bolt into the latched state, and the other of the manually operable input switches being provided for operating the drive means for urging the bolt into the unlatched state.

29. A lock as claimed in any preceding claim in which a first override means is provided for overriding the drive means for facilitating urging the bolt into at least one of the latched and the unlatched states independently of the drive means.

30. A lock as claimed in Claim 29 in which the first override means is adapted for urging the bolt between the latched and the unlatched state.

31. A lock as claimed in Claim 29 or 30 in which the first override means comprises a key operated barrel actuator.

32. A lock as claimed in Claim 31 in which the key operated barrel actuator is co- operable with the drive transmission means for urging the bolt between the latched and the unlatched state.

33. A lock as claimed in any preceding claim in which a second override means is provided for overriding the drive means for facilitating urging of the bolt into at least one of the latched and the unlatched states independently of the drive means.

34. A lock as claimed in Claim 33 in which the second override means comprises a knob mounted on the bolt.

35. A lock as claimed in any of Claims 29 to 34 in which the slipping clutch is configured to slip when the force on the bolt is greater than the force which could be applied to the bolt during an unauthorised attempt to urge the bolt from the latched state, but is configured to slip at a force which is not so great as to prevent the bolt being urged from the latched state by one of the first and second override means.

36. A lock as claimed in any preceding claim in which a portion of the bolt is urgeable from the housing on one side thereof when the bolt is in the latched state for engaging the external receiver.

37. A lock as claimed in any preceding claim in which respective portions of the bolt are alternately urgeable outwardly of the housing on respective opposite sides thereof into respective latched states so that the lock is suitable for mounting on a right-handedly hinged or a left-handedly hinged closure.

38. A lock as claimed in Claim 37 in which the bolt is an elongated bolt, and the respective portions which are alternately urgeable outwardly of the housing on the respective opposite sides thereof are formed by respective opposite end portions of the bolt.

39. A lock as claimed in Claim 37 or 38 in which an opening is provided in respective opposite sides of the housing for accommodating the bolt therethrough on the respective opposite sides thereof.

40. A lock as claimed in any preceding claim in which the drive means is responsive to a signal indicative of a door with which the lock is associated being in a closed state for urging the bolt into the latched state.

41. In combination a lock as claimed in any preceding claim and a discrete handheld transmitter for transmitting appropriately encoded signals for reception by the receiver of the lock for operating the bolt thereof into one of the latched and the unlatched states.

42. A combination of a plurality of the locks as claimed in any preceding claim in which the microprocessor of one of the locks is configured as a master microprocessor, and the microprocessors of the other locks are configured as slave microprocessors, so that the locks, the microprocessors of which have been configured as slave microprocessors are operable for urging the respective bolts thereof into one of the latched and the unlatched states in response to a signal from the lock, the microprocessor of which is configured as a master microprocessor.