ALARM ASSEMBLY

Abstract: An alarm assembly for use in child equipment intended to be operated by an adult, comprising an actuator (10) for actuating the or part of the equipment, first sensing means (18) operable to sense initial movement of the actuator, an alarm drive unit (22) coupled to the first sensing means and operable to issue an alarm signal on sensing of initial movement of the actuator, and second sensing means (20) operable to sense a further predetermined movement of the actuator and coupled to the alarm drive unit, the alarm drive unit being operable to prevent or stop the alarm signal on sensing of the further movement of the actuator.

Description: ALARM ASSEMBLY The present invention relates to an alarm for use, for example, in nursery gates. Various devices are provided for nursery gates and other such equipment to prevent or at least substantially reduce the risk of a child opening the gate or otherwise tampering with the equipment. For example, a gate release mechanism may be provided with a spring or similar device which will only allow actuation of the release mechanism upon application of a force significantly in excess of the strength of a child's hands. Other tamper-proof devices may also or in the alternative be provided. The present invention seeks to provide an alarm for child equipment intended to be operated solely by an adult, such as a nursery gate. According to an aspect of the present invention, there is provided an alarm assembly for use in child equipment intended to be operated by an adult, comprising an actuator for actuating the or part of the equipment, first sensing means operable to sense initial movement of the actuator, an alarm drive unit coupled to the first sensing means and operable to issue an alarm signal on sensing of initial movement of the actuator, and second sensing means operable to sense a further predetermined movement of the actuator and coupled to the alarm drive unit, the alarm drive unit being operable to prevent or stop the alarm signal on sensing of the further movement of the actuator. A small child tampering with the actuator would only actuate the first sensing means, thereby causing the alarm drive unit to issue an alarm signal. Only on full movement of the actuator would the alarm signal be suppressed. The actuator is preferably normally provided with means to prevent full movement of the actuator by a child. For example, such a means may be a spring which can only be overcome by the exertion of a force greater than that which can be produced by a small child, such as a force of around 50 Newtons or more. Thus, a small child would not be able to actuate the second sensing means by not being able to move the actuator through its full actuating motion. In this manner, a small child would not be able to stop the alarm signal . Preferably, the alarm signal is an audible signal, the assembly being provided with an acoustic transducer such as a piezo-electric transducer coupled to the alarm drive unit. In order to prevent any sounding of the alarm upon proper movement of the actuator, the alarm drive unit may provide a delay before generating the alarm signal after detection of the initial actuator movement. Such a delay may be, for example, between about 0.25 and 2 seconds, but is preferably between about 0.5 and 1.5 seconds. Where the sensing mechanism requires it, the delay may be longer than 2 seconds . In the case of a latch release handle for a nursery gate, in which the actuator is provided in the handle by means of a depressible trigger, a half second delay would generally be more than sufficient to prevent sounding of the alarm on operation of the trigger by an adult. However, a small child would not be able to overcome the force of the spring to prevent sounding of the alarm. The assembly may be provided with means to switch off the alarm once actuated. Preferably, the assembly is self-powered by means of a battery, although it may be mains powered if appropriate. Devices other than a spring for preventing full movement of the actuator by a small child can be used, such as any form of tamper-proof latch or other device conventional in the art . Embodiments of the present invention are described below, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a cross-sectional view of a first embodiment of a handle trigger mechanism for use with a nursery gate; Fig. 2 is second embodiment of a handle trigger mechanism for use with a nursery gate shown with a portion of the outer cover removed; Figs. 3 to 5 are further views of the handle trigger mechanism of Fig. 2 with a portion of the outer cover removed; and Fig. 6 is a view of a third embodiment of a handle trigger mechanism with an alternative switching arrangement. The type of handle shown in the Figures is intended for use in a nursery gate which is provided with a latch (not shown) to lock the gate in a closed position. With reference to Fig. 1, the handle 10 is provided with a trigger 12 which can be depressed into the handle 10 to release the latch. In order to prevent a small child from operating the trigger 12 fully and therefore to release the gate, there is provided a leaf spring 14 which exerts a biasing force of, preferably, around 50 Newtons for full depression of the trigger 12. The term "full depression" is intended to refer to the amount of depression of the trigger 12 into the handle body 10 required to cause release of the latch of the nursery gate. The handle 10 is provided with an alarm system 16 which includes first and second switches 18 and 20 respectively. An alarm drive unit 22, in this embodiment provided within the trigger cavity, is coupled to the two switches 18, 20 and also to a piezo-electric transducer 24. A battery 26 provides power to the alarm drive unit 22. Not shown in the Figures is a mechanism for disabling the alarm once actuated. In one embodiment, this mechanism may be provided simply by depressing the trigger 12 fully to actuate the second switch 20. The battery 26 is provided within a battery compartment 30, the lower end part 32 thereof being releasable by release of a screw 34. Coupling the first and second switches 18, 20 to the trigger 12 is a pivoting arm 36 which cooperates with a driving pin 38 provided on the trigger handle 12. The pivoting arm 36 includes a first end which cooperates with the first switch 18 to depress and release, as the case may be, the actuator of the switch 18. The actuator of the switch 18 may be provided with a release return mechanism such as a spring to cause the switch 18 to switch to its "off" state, with its actuator in an extended position, when the pivoting arm 36 does not apply pressure to its actuator. The second end of the pivoting arm 36 operates with the switch 20 in similar manner. Also provided on the pivoting arm 36 are first and second cam surfaces which cooperate with the driving pin 38 so as positively to move the pivoting arm 36 in dependence upon the position of the trigger 12. When the trigger 12 is in its rest position, the driving pin 38 urges the pivoting arm 36 to depress the actuator of the switch 18, representing a steady state condition of the trigger 12. If the trigger 12 is depressed to move into the handle 10 by a small amount, the driving pin 38 becomes disengaged from the lower cam surface of the pivoting arm 36, thereby enabling the actuator of the first switch 18 to move out into a switch "off" position. The alarm drive unit 22 detects the change in the state of the switch 18. If nothing more occurs within, in this example, half a second of sensing the changing condition of the switch 18, the alarm drive unit 22 issues an alarm signal to the piezo-electric transducer 24 so as to generate an audible alarm. When the trigger 12 is moved beyond an initial amount, the drive pin 38 abuts the upper cam surface of the pivoting arm 36 (as shown in the Figure) to depress the actuator of the second switch 20, causing this switch to toggle to a "on" position. This change in condition of the second switch 20 is detected by the alarm drive unit 22 to cease generation of the alarm signal. If the second switch 20 changes state within the pre-set half-second period, the alarm signal is not generated. On the other hand, if the switch 20 is toggled only after the pre-set period, the system may be designed to switch off the alarm at the time of toggling of the second switch 20. With reference to Figs 2-5, another embodiment houses certain internal components of the alarm mechanism outside the handle casing and employs different switching arrangements. The handle 10 is shown provided on an upper gate member 40 and the position of the various alarm components with respect thereto is shown schematically in Fig. 2 by broken lines. The switching arrangement 42 is positioned substantially within the outer casing 44 of the handle 10, whereas the piezo-electric transducer 24 and battery 26 are housed substantially within the upper gate member 40. The switching arrangement consists of contact element 50 mounted on a movable portion of the handle trigger mechanism and first and second switches 18' and 20' provided in a spaced apart arrangement on an opposed PCB 52. The positions of the first and second switches 18', 20' are such that none or either of their actuators can be selectively engaged by contact element 50 as it moves during motion of the trigger mechanism. As with the embodiment of Figure 1, actuation of the trigger 12 from its rest position through an initial movement and beyond encompasses three switch conditions corresponding to "off", "alarm" (subject to delay) and "off", respectively, depending on which, if any, of switches 18' and 20' are engaged by contact element 50. In this example, the arrangement of switch components is such that in normal operation the time taken to go from the actuator of switch 18' to that of switch 20' is less than about 0.5 seconds. Therefore, a delay of about 0.5 seconds between an initial amount of movement and sounding of the alarm is sufficient to permit facile operation by an adult. Fig. 3 shows the trigger in its rest position in which contact element 50 depresses the actuator of switch 18'. This configuration represents a steady state condition in which the alarm is "off" . Fig. 4 shows the same switch after an initial movement of trigger 12 resulting in release and therefore a change of state of the actuator of the first switch 18' . Contact element 50 is in a position between switches 18' and 20' with neither switch actuator engaged. This configuration corresponds to "alarm", subject to a predetermined delay. If the trigger is not fully depressed within about 0.5 seconds, an alarm signal is generated and this cannot be cancelled by releasing the trigger to once again engage the actuator of swi-tch 18' . In Fig. 5, the trigger has moved beyond the initial amount to an extent effective to unlatch the gate. Contact element 50 now engages the actuator of switch 20', corresponding to a second "off" position. Movement through to this second off position will stop generation of the alarm signal if it has been initiated or prevent generation of the alarm signal altogether if the delay has not yet expired. In one modification, the element 50 is electrically conducting and switches 18' and 20' of Figs. 2-5 are replaced by similarly conducting contact pads. A progressive sliding movement of element 50 as the trigger is depressed moves element 50 over the opposed contact pads and selectively through configurations corresponding to "off", "alarm" (subject to delay) and "off" in a manner similar to that described above. Fig. 6 shows a handle mechanism having a retaining bar 60 for supporting the trigger 12, buzzer alarm 24 and locking rod 62. The switching arrangement includes first and second switches 18" and 20", respectively, and a rigid member 60 provided on a movable portion of the trigger 12. Switches 18" and 20" are fixedly supported on an inner portion of the handle casing 44, whereas member 60 is part of the trigger 12 and moves as the trigger 12 is actuated. With the trigger 12 in its rest position, member 60 depresses the actuator of the switch 18", representing a steady state condition of the trigger 12. If the trigger is depressed to move into the handle by a small amount, member 60 becomes disengaged enabling the actuator of switch 18" to change state. If nothing further occurs within a predetermined delay period, the alarm drive unit 22 issues an alarm signal to the piezo- electric transducer 24. When the trigger is moved beyond an initial amount, member 60 depresses the actuator of switch 20", causing this switch to change state and stop generation of the alarm signal. It will be apparent that switching configurations are not limited to those disclosed herein and that the positions of the various components are completely arbitrary. In modifications, there may be provided a different mechanism for switching off the alarm once it has been actuated. This may be by a separate switch located out of reach of a small child or by a pre-set logic pattern of movement of the trigger assembly, detectable by the drive unit 22. Such a pre-set pattern may, for example, be a certain number of actuations of the second switch 20 within a defined period, such as two actuations within a period of a second or so. It will be apparent that a small child would not be able to overcome the force of the leaf or other spring 14 if tampering with the trigger 12. However, in preferred embodiments, the child would be able to move the trigger 12 to such an extent to toggle the first switch 18, thereby to provide a warning that the child is playing with the nursery gate. It will be apparent that the alarm could be used for other types of child equipment intended to be operated solely by an adult, such as mechanisms of push-chairs, door handles and the like.

Claims: CLAIMS 1. An alarm assembly for use in child equipment intended to be operated by an adult, comprising an actuator (12) for actuating the or part of the equipment, first sensing means (18; 18'; 18") operable to sense initial movement of the actuator, an alarm drive unit (24) coupled to the first sensing means and operable to issue an alarm signal on sensing of initial movement of the actuator, and second sensing means (20; 20'; 20") operable to sense a further predetermined movement of the actuator and coupled to the alarm drive unit, the alarm drive unit being operable to prevent or stop the alarm signal on sensing of the further movement of the actuator. 2. An alarm assembly as in claim 1, wherein the alarm drive unit (12) is operable to generate a signal in response to initial movement only after a predetermined delay. 3. An alarm assembly as in claim 1 or 2 , comprising means (14; 14'; 14") to prevent the further predetermined movement of the actuator by a child. 4. An alarm assembly as in any of claims 1 to 3 , wherein the actuator comprises a trigger mechanism (12) movement of which beyond an initial movement is hindered by a biasing force which is too strong for a child to overcome, but facile for an adult to overcome. 5. An alarm assembly as in claim 4, wherein a biasing force in -the region of 50 Newtons or more is provided by a spring (14; 14'; 14") or equivalent means. 6. An alarm assembly as in any preceding claim, comprising an acoustic transducer (24) for generating an audible alarm signal . 7. An alarm assembly as in any preceding claim, wherein the first and second sensing means comprise a switching arrangement (18, 20; 18', 20'; 18", 20") including a contact element (50) and spaced apart first and second switching means (18, 20; 18', 20'; 18", 20"), wherein movement of the actuator (12) is operable to move the contact element in or out of engagement with the or each switching means selectively. 8. An alarm assembly as in claim 7, wherein when the actuator (12) is in a rest position the first switch means (18; 18',- 18") only is engaged, when the actuator is moved by an initial amount neither switch is engaged, and when the actuator is moved by an amount effective to unlock the gate the second switch means (20; 20'; 20") only is engaged. 9. An alarm assembly as in any of claims 1-6, wherein the first and second sensing means comprise a contact element (50) and first and second contact pads, wherein movement of the actuator (12) is operable to slide the contact element in or out of engagement with the or each contact pad. 10. A nursery gate comprising an alarm assembly according to any preceding claim.

Inventors: ELAM JOHN MICHAEL, ELAM, JOHN, MICHAEL
Applicants: BETTACARE LTD, ELAM JOHN MICHAEL, BETTACARE LIMITED, ELAM, JOHN, MICHAEL
Application year: 1998
Main classification: G08B13
IPC codes: G08B13, G08B21