GB1592739A - Latches and locks - Google Patents

Description

(54) IMPROVEMENTS IN AND RELATING TO LATCHES AND LOCKS (71) We, ACCESS CONTROL SYSTEMS PTY. LTD. a company incorporated under the laws of the State of Victoria, Commonwealth of Australia, of 143 Queen Street, Melbourne, Victoria, Australia do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed to be particularly described in and by the following statement: This invention relates to latches and locks and has particular, but not exclusive, application to door latches which can be released by electrical signals.

The invention is particularly concerned with door locks and latches of the type in which a bolt member projects from an outer edge of the door to project into a cavity in a catch member or assembly installed in the door frame. In a simple installation the door frame will be fitted with a fixed catch member. Particularly in cases where the door is to be released electrically, however, the catch member may be movable between an operative position in which it can serve the normal catch function and an in-operative catch position in which to enable release of the door no matter in what position the co-operating lock or latch bolt.

In many door lock or latch installations it would be most desirable to provide some means for indicating positively that the bolt member had definitely engaged the catch cavity and that the door was therefore securely locked. Such applications can arise with fixed catch installations but more often with moving catch installations in which the door is released by electrical signals. The present invention provides simple means to provide a positive indication of interengagement between a bolt member and a catch cavity.

According to the present invention, there is provided a door catch assembly mountable on the frame of a door having a lock structure including a lock bolt which can project beyond the outer edge of the door; the catch assembly having a cavity to receive the said lock bolt whereby to hold the door in its closed position, an emitter of electro-magnetic radiation at one side of the said cavity and a sensor at the other side of the cavity to receive at least some of the electro-magnetic radiation emitted by the said emitter, and operable to generate an electric output on receipt of such radiation, transmission of the electromagnetic radiation from the emitter to the sensor across the cavity being interrupted by the lock bolt when the lock bolt is in engagement with the catch cavity.

The catch assembly may be a catch mechanism of the type having a catch member movable between operative and inoperative positions. Specifically, the catch assembly may be comprised of a body, a catch member mounted on the body so as to be movable between an operative position in which to define a wall of said catch cavity and in which to serve as a catch for the lock bolt and an inoperative position in which to release the lock bolt, detent means conditionable to hold the catch member in said operative position but releasable to allow the catch member to move to its inoperative position and power means to control the condition of the detent means.

Preferably, the emitter is an emitter of infra-red electro-magnetic radiation and the sensor generates an electric output on irradiation with such infra-red electro-magnetic radiation. The emitter may, for example, be constituted by an emitting diode and the sensor may be constituted by a photo-transistor.

In order that the invention may be more fully explained, one particular embodiment will be described in detail with reference to the accompanying drawings, in which: Figure I is a perspective view of a previously known latch mechanism having a moving catch member; Figure 2 is a cross-section on the line 2-2 in Figure 1 which also shows a door fitted with a dead-lock to co-operate with the latch mechanism; Figure 3 is a cross-section generally similar to that of Figure 2, but showing the mechanism in a different condition; Figure 4 is a cross-section on the line 4-4 in Figure 2; Figure 5 is a cross-section on the line 5-5 in Figure 3; Figure 6 is a perspective view of a lever from the latch mechanism;; Figure 7 is a scrap perspective view of a part of the latch mechanism which includes a keeper member Figure 8 is a perspective view of a pivoting catch member from the mechanism Figure 9 is a cross-section showing a modification which can be incorporated in the mechanism and is to be contrasted with Figure 2; Figure 10 illustrates a modification of the mechanism in accordance with the present invention by the provision of an infra-red electro-magnetic radiation emitter and an appropriate radiation sensor; Figure 11 is a cross-section on the line 11-11 in Figure 10; Figure 12 is a cross-section corresponding to Figure 11 but showing the bolt of the dead-lock withdrawn; Figure 13 illustrates one possible electrical circuit for the radiation emitter and sensor; and Figure 14 illustrates an alternative electric circuit by which the radiation sensor and a door actuated micro-switch act jointly to provide an alarm function.

The mechanism illustrated by Figures 1 to 9 of the drawings is indicated generally as 11 and is designed for installation in a door frame 12 to co-operate with a conventional dead-lock 13 fitted to a door 14 mounted within the frame. More particularly, mechanism 11 includes a catch member 16 which can co-operate with the spring-loaded bolt 17 of lock 13 to provide a locking function. However, this catch member 16 can be pivoted to an inoperative position so as to release bolt 17 and permit the door to open. The condition of catch member 16 is controlled by an electric solenoid included in the mechanism.

Mechanism 11 has a body 15 comprised of a hollow casing 18 and a front plate 22. Casing 18 includes a removable side plate 19 held in position by screws 23 and it is fastened to front plate 22 by means of screws 21. Body 15 has a lower relatively deep slot 25 to register with the bolt 17 of lock 13 as door 14 swings to its closed position and an upper relatively short slot 26 to register with the dead-lock actuator bar 27 of the lock 13 as will be more fully explained below.

Catch member 16 is mounted across slot 25. More particularly it is pivotaly mounted on a pivot pin 28 which traverses slot 25 and extends into holes in casing wall portions 30, 35 which define upper and lower walls of the slot. It is shaped generally as a long bar of L-shaped transverse cross-section, one limb 31 of which is mounted on the pivot pin 28 and the other limb 32 of which serves as the catch for lock bolt 17. Limb 31 has a bore 33 extending through it to receive pivot pin 28 and is counter-bored at each end to provide end recesses 34 to house a pair of torsion springs 36 disposed about pin 28. Springs 36 have short end arms 37 which project into slots 38 formed in the walls of recesses 34 of catch member 16 and rather longer arms 38 which react against the side wall 40 of casing 18.They bias catch member 16 toward the position shown in Figures 1, 2 and 4 in which position the flat end surface 45 of its limb 31 abuts the casing side wall 40 to limit pivoting movement and its limb 32 is generally parallel with wall 40 and can serve as a catch for the spring loaded lock bolt 17. This is most clearly illustrated in Figure 4 in which the phantom lines indicate the position of the door and the lock bolt as the door approaches the fully closed position and the full lines show the position of these components when the door is fully closed. The outer end of limb 32 of the catch member is chamfered to provide a sloping striker face 41 which is struck by the lock bolt as the door is closed to force the lock bolt back against its spring loading.As the door reaches its fully closed position the lock bolt is forced outwardly by its spring loading to locate behind the side face 42 of catch limb 32. At the same time the dead-lock actuator bar 27 of the lock enters slot 26 and strikes a ramp surface 55 formed in front plate 22 at the end of the slot so as to be actuated to move the dead-lock pin within the lock in the usual manner.

As will be described below catch member 16 can be locked in position so that face 42 of its limb 32 acts as a locking face to prevent opening of the door. However, catch member can be released so that it can be pivoted about pivot pin 28 to allow release of the door in the manner shown in Figure 5. The locking and release of catch member 16 is achieved through a detent mechanism comprised of a lever 43 and a keeper member 44 which is controlled by means of a solenoid 46.

Lever 43 is in the form of a long bar provided at one end with a bore 48 to receive a pivot pin 47 by which it is pivotally mounted on casing 18. It is disposed within casing 18 immediately behind catch member 16 and it extends longitudinally of the catch member.

More specifically, it is arranged to engage the outer corner part 49 of the catch member at the junction between the two limbs 31, 32. This outer corner part of the catch member serves as a cam to engage lever 43 and pivot it about its pivot pin 47 when catch member 16 is pivoted between its operative and inoperative positions. It has a cam surface 51 which is cylindrically curved about the pivot axis of catch member 16 and a leading cam edge 52 which subtends an angle of rather more than 90" to surface 51.

Lever 43 is biased into firm engagement with catch member 16 by two helical compression springs 53 acting directly between the lever and a rear wall portion 54 of casing 18. It is formed from rectangular bar stock so as to have flat front and side faces 56, 57 but one corner edge 58 is relieved by a saw-tooth notch 59 to form a flat triangular cam face 61 which engages the leading cam edge 52 of catch member 16 when the catch member is in its operative position. This condition of the catch member 16 and lever 43 is illustrated by Figures 2 and 4. It will be seen that lever 43, although extending generally longitudinally of catch member 16, subtends a slight acute angle to it and its triangular cam face 61 lies flat against an end part of cam edge 52.Keeper member 44 acts to enable lever 43 to be locked in this condition or released according to the supply of electrical signals to solenoid 46.

Keeper member 44 is shaped generally as a bell crank. It has two mutually perpendicular arms 62, 63 and is pivotally mounted on body 18 by a pivot pin 64. Its arm 62 is transverse to lever 43 and has a notch 66 to engage the outer end of the lever so as to provide a detent action holding the lever in the position shown in Figure 2. Notch 66 is generally of saw-tooth shape to define a sloping catch face 67 and the outer end of lever 43 is notched at 68 so as to be shaped as a tooth having a tooth face 69 to engage the catch face 67 of the keeper arm.

Keeper member 44 may be held in its keeping position shown in Figure 2 by the action of solenoid 46. This solenoid has a coil 71 wound on a body 72 about a central core 73. It is mounted in casing 18 so that when energised its magnetized core will attract the outer end of the actuator arm 63 of keeper member 44 to hold the keeper member in its keeping position.

Its core is connected to a mild steel backing plate 50 which extends close to the outer end of arm 63 so as to direct magnetic flux through the keeper member and thus increase the attractive force of the solenoid. As shown in Figure 2 a slight clearance is maintained between the solenoid core and arm 63 to prevent sticking when the solenoid is de-energized.

Keeper member 44 is biased away from its keeping position by a biasing spring 74. This spring has a coiled portion 76 looped around the keeper member pivot pin 64 and two end arms 77, 78 which are engaged respectively with the casing 18 and a hole in keeper arm 62.

When solenoid 46 is energized it holds the keeper member in its keeping position against the action of biasing spring 74. However, when solenoid 46 is de-energized spring 74 acts to pivot keeper member 44 to the position shown in Figure 3 in which its actuator arm 63 is held against an adjustable stop screw 74 and its keeper arm 62 is drawn away from keeping engagement with the outer end of lever 43. The only action then holding catch member 16 in its catch position is that provided by springs 53 acting on lever 43. However, because of the cam action between lever 43 and cam portion 49 of the catch member only a light force is needed on catch member 16 to pivot it away from its operative position to force lever 43 back against its biasing springs to the inoperative position shown in Figures 3 and 5.At the start of such movement of the catch member its cam edge 52 acts on the triangular cam face 61 of lever 43 to force the lever backwardly against its biasing springs until the cylindrical curved cam surface 51 can engage the flat front face 56 of the lever as shown in Figure 5.

The rear part of casing 18 has a compartment 81 which houses a micro-switch 82 the actuator 83 of which is engaged by a bracket 84 on lever 43 when the lever is moved consequent to pivoting of catch member 16 to its inoperative position.

Electrical leads from solenoid 46 and micro-switch 82 are connected within casing 18 to a terminal block 86 which is located partly within compartment 82 but extends rearwardly through an opening in the back wall 87 of the casing and is fitted outside the casing with a series of terminals 88 for connection to external wiring.

The catch mechanism illustrated in Figures 1 to 8 will operate to hold the door locked for so long as solenoid 46 is energized. By de-energizing the solenoid, catch member 16 is freed and the door can be opened. The mechanism has a wide range of applications. For example it may be used in a fire door installation in order to maintain a fire door in a normally locked condition but to release the door in response to a signal created by a smoke or heat detector acting through any suitable relay to interrupt the supply of power to solenoid 46. In other applications the supply of power to solenoid 46 may be interrupted by operation of a push button located inside a building or by a signal derived from a reader device in response to a magnetically coded key or card. Micro-switch 82 may be used to derive a warning or alarm signal each time that the door is opened.

Figure 9 illustrates a modification by which the mechanism is adapted to keep a door locked when the solenoid is de-energized and releases the door when the solenoid receives an electrical signal. The components of the mechanism are not altered but the setting of spring 74 is altered to bias keeper member 44 toward its keeping position and solenoid 46 is displaced through 90" from its previous position so as to act directly on keeper arm 62 rather than on arm 63 of the keeper member. The re-setting of biasing spring 74 involves insertion of its arm 77 in a hole drilled in arm 63 instead of in the hole in arm 62 and the other spring arm 78 acts against a different part of casing 18.In this case keeper arm 62 is normally held by spring 76 in keeping engagement with the upper end of lever 43 by the action of spring 74 but is lifted to free the lever when solenoid 46 is energized. Stop screw 79 is set to engage arm 63 of keeper member 44 before arm 62 can engage the solenoid core so that even when the solenoid is energised there will be a slight clearance between its core and arm 62.

Mechanism 11 is set into a recess 91 in door frame 12 and may be held in position by conventional wood screws passed through counter-sunk holes 92 in front plate 22. A groove 93 may be formed in the door frame to receive the projecting part of terminal block 86 and the external wiring.

As shown in Figures 4 and 5 side plate 19 of casing 18 has an inturned lip 96 which abuts cam surface 51 of catch member 16 and as the catch member pivots the cylindrical surface 51 simply slides on lip 96. Thus contact is maintained between catch member 16 and lip 96 at all times to seal off the interior of the casing and prevent tampering by insertion of an instrument between the catch member and the casing.

Figures 10 to 12 show a modification incorporated in the catch mechanism in accordance with the present invention. The modification involves the installation of an infra-red radiation emitter 101 and a radiation sensor 102. Emitter 101 may be a conventional light emitter diode and it is installed in an appropriate housing 103 at one side of the cavity 104 which receives the lock bolt 17. One side of cavity 104 is defined by the limb 32 of catch member 16 when the catch member is in its operative position. The light emitting diode is disposed so that it directs a beam of infra-red radiation across the cavity 104 and the collector transistor 102 is located at the other side of the cavity so as to be irradiated by that beam in the event that lock bolt 17 is withdrawn from the cavity as in Figure 12.However, when lock bolt 17 is disposed within cavity 104 as shown in Figure 11 to properly lock the door the beam of infra-red radiation is interrupted by the lock bolt so that sensor transistor 102 is not irradiated and cannot produce an output.

Figure 13 illustrates a simple electric circuit for the light emitting diode 101 and the sensor transistor 102. A BP x 25 transistor is a suitable sensor. Both diode 101 and transistor 102 are connected between a line 105 connected at 106 to a 24 volt DC supply and a line 107 which is earthed at 108. Diode 101 is connected in series with a 260 OHM resistor 110 and since it is permanently connected between the supply and earth it emits radiation continuously. The sensor transistor 102 is connected in series with a 1.5K resistor 109 and it controls the condition of a DN 3645 transistor 111 which is connected in series with a relay coil 112 between lines 105 and 107.

When transistor 102 is irradiated with infra-red radiation from diode 101 it renders diode 111 conductive so that current flows through relay coil 112. The relay then operates to provide a warning signal indicating that lock bolt 17 is not within the catch cavity 104. In a typical installation the relay would operate to cause illumination of a red warning light. This would light up when the door was opened and would remain illuminated until the door had been closed and the lock bolt properly registered with the catch cavity 104.

Figure 14 illustrates a modification of the circuit which enables a door actuated switch to be incorporated to provide a more sophisticated warning system. The circuitry illustrated in Figure 14 may be connected into the circuit of Figure 13 in place of the relay coil 112 so that the terminals A and B are the same in both Figures 13 and 14. In this case the door actuated switch 113 provides a signal to line 114 when the door is closed. The circuitry previously described with reference to Figure 13 will provide a signal to line 115 when the lock bolt is out of registration with catch cavity 104. Lines 114, 115 are connected to an exclusive OR gate 116 and 220 OHM resistors 117, 118 and earthed Zenor diodes 119, 120 are provided to cdntrol the signals provided to the gate. The output of gate 116 is supplied through a line 121 via a time delay device comprised of a 25K resistor 122 a 1ZF capacitor 123, shunt line 124 and an AND gate 125. This device provides a time delay of about 0.1 sec. so that an output in the line 121 must be maintained for longer than this time interval in order to provide an output signal in the line 126. This output is applied through a 600 OHM resistor 127 to the gate of a silicon controlled rectifier 128 which is normally non-conductive but when fired by an output signal in line 126 becomes conductive to provide a conductive path through relay coil 129 which then operates to provide a warning signal until such time as a resetting switch 131 is actuated.

Exclusive OR gate 116 will produce an output signal in line 121 only in the event that a signal is produced in one of lines 114, 115 and not in the other. When the door is opened there will be signals in both lines 114, 115 and there will be no alarm signal and the only time that an alarm signal will be generated will be if the door should be closed but the lock bolt not in proper registration with catch cavity 104. This condition would arise, for example, if the lock bolt were deliberately jammed in its retracted position prior to closure of the door or if an attempt were made to wedge it open as a preliminary step in opening the door. The delay of 0.1 sec. provided by the time delay device is sufficient to cover any time difference between operation of the door actuated switch and the radiation detector on normal closure of the door.

From the above description, it will be appreciated that the inclusion of a radiation emitter and sensor in accordance with the present invention in order to sense correct positioning of a lock bolt enables greatly increased security in a door access control system. However the illustrated embodiment of the invention has been advanced by way of example only and the invention is not limited to this particular construction. It would, for example, be possible to provide an appropriate emitter and sensor in a conventional mechanically operated door locking arrangement incorporating a fixed catch member. Although it is preferred to use infra-red radiation in order to avoid interference by radiation in the visible spectrum this is not essential and radiation of other wave lengths could be used.It is accordingly to be understood that the invention is not limited to the details of the illustrated construction and that many modifications and variations will fall within the scope of the appended claims.

WHAT WE CLAIM IS: 1. A door catch assembly mountable on the frame of a door having a lock structure including a lock bolt which can project beyond the outer edge of the door; the catch assembly having a cavity to receive the said lock bolt whereby to hold the door in its closed position, an emitter of electro-magnetic radiation at one side of the said cavity and a sensor at the other side of the cavity to receive at least some of the electro-magnetic radiation emitted by the said emitter, and operable to generate an electric output on receipt of such radiation, transmission of the electro-magnetic radiation from the emitter to the sensor across the cavity being interrupted by the lock bolt when the lock bolt is in engagement with the catch cavity.

2. A door catch assembly as claimed in claim 1, wherein the said emitter is an emitter of infra-red electro-magnetic radiation and the sensor generates an electric output on irradiation with such infra-red electro-magnetic radiation.

3. A door catch assembly as claimed in claim 1 or claim 2, wherein the emitter is a light emitting diode and the sensor is a photo-transistor.

4. A door catch assembly as claimed in any of claims 1 to 3, wherein the catch assembly comprises a body, a catch member mounted on the body so as to be movable between an operative position in which to define a wall of the said catch cavity and in which to serve as a catch for the lock bolt, and an inoperative position in which to release the lock bolt, detent means conditionable to hold the catch member in the said operative position but releasable to allow the catch member to move to its inoperative position, and power means to control the condition of the detent means.

5. A door catch assembly as claimed in any one of claims 5 to 8, wherein there is further provided a warning light electrically connected into an electric circuit which includes the said sensor such that the warning light is illuminated when the lock bolt is not engaged with said cavity but is not illuminated when the lock bolt is engaged with the cavity.

6. A door catch assembly as claimed in any one of claims 5 to 8, wherein there is further provided a door actuated switch which has one condition when the door is closed and another condition when the door is open and wherein the door actuated switch and the sensor are connected into an electrical circuit including an alarm signal generator such that an alarm signal is generated if the door is closed but the lock bolt is not in proper registration with the catch cavity.

7. A door catch assembly as claimed in claim 6, wherein the said electrical circuit includes an OR gate connected to receive input signals from the door actuated switch and the sensor and operative to provide output signals controlling the generation of the alarm signal.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. signal is produced in one of lines 114, 115 and not in the other. When the door is opened there will be signals in both lines 114, 115 and there will be no alarm signal and the only time that an alarm signal will be generated will be if the door should be closed but the lock bolt not in proper registration with catch cavity 104. This condition would arise, for example, if the lock bolt were deliberately jammed in its retracted position prior to closure of the door or if an attempt were made to wedge it open as a preliminary step in opening the door. The delay of 0.1 sec. provided by the time delay device is sufficient to cover any time difference between operation of the door actuated switch and the radiation detector on normal closure of the door. From the above description, it will be appreciated that the inclusion of a radiation emitter and sensor in accordance with the present invention in order to sense correct positioning of a lock bolt enables greatly increased security in a door access control system. However the illustrated embodiment of the invention has been advanced by way of example only and the invention is not limited to this particular construction. It would, for example, be possible to provide an appropriate emitter and sensor in a conventional mechanically operated door locking arrangement incorporating a fixed catch member. Although it is preferred to use infra-red radiation in order to avoid interference by radiation in the visible spectrum this is not essential and radiation of other wave lengths could be used.It is accordingly to be understood that the invention is not limited to the details of the illustrated construction and that many modifications and variations will fall within the scope of the appended claims. WHAT WE CLAIM IS:

1. A door catch assembly mountable on the frame of a door having a lock structure including a lock bolt which can project beyond the outer edge of the door; the catch assembly having a cavity to receive the said lock bolt whereby to hold the door in its closed position, an emitter of electro-magnetic radiation at one side of the said cavity and a sensor at the other side of the cavity to receive at least some of the electro-magnetic radiation emitted by the said emitter, and operable to generate an electric output on receipt of such radiation, transmission of the electro-magnetic radiation from the emitter to the sensor across the cavity being interrupted by the lock bolt when the lock bolt is in engagement with the catch cavity.

2. A door catch assembly as claimed in claim 1, wherein the said emitter is an emitter of infra-red electro-magnetic radiation and the sensor generates an electric output on irradiation with such infra-red electro-magnetic radiation.

3. A door catch assembly as claimed in claim 1 or claim 2, wherein the emitter is a light emitting diode and the sensor is a photo-transistor.

4. A door catch assembly as claimed in any of claims 1 to 3, wherein the catch assembly comprises a body, a catch member mounted on the body so as to be movable between an operative position in which to define a wall of the said catch cavity and in which to serve as a catch for the lock bolt, and an inoperative position in which to release the lock bolt, detent means conditionable to hold the catch member in the said operative position but releasable to allow the catch member to move to its inoperative position, and power means to control the condition of the detent means.

5. A door catch assembly as claimed in any one of claims 5 to 8, wherein there is further provided a warning light electrically connected into an electric circuit which includes the said sensor such that the warning light is illuminated when the lock bolt is not engaged with said cavity but is not illuminated when the lock bolt is engaged with the cavity.

6. A door catch assembly as claimed in any one of claims 5 to 8, wherein there is further provided a door actuated switch which has one condition when the door is closed and another condition when the door is open and wherein the door actuated switch and the sensor are connected into an electrical circuit including an alarm signal generator such that an alarm signal is generated if the door is closed but the lock bolt is not in proper registration with the catch cavity.

7. A door catch assembly as claimed in claim 6, wherein the said electrical circuit includes an OR gate connected to receive input signals from the door actuated switch and the sensor and operative to provide output signals controlling the generation of the alarm signal.

8. A door catch assembly substantially as hereinbefore claimed in claim 1 and described

with reference to Figures 1 to 12 of the accompanying drawings.