[0001] THE PRESENT INVENTION relates to an alarm device and more particularly the present
invention relates to an alarm device which can be utilised to provide an alarm whenever
an item such as a suitcase or bag is opened by an unauthorised person. Whilst the
invention will be described with reference to an alarm adapted for use in a suitcase,
it is to be appreciated that an alarm in accordance with the invention may also be
utilised, if desired, to provide an alarm whenever a drawer or cupboard is opened
by an unauthorised person.
[0002] According to this invention there is provided an alarm device, said alarm device
comprising an arming and dis-arming arrangement, means to close a switch when part
of the device is permitted to move relative to another part of the device, and an
alarm signal generator actuated on closure of said switch when the device is armed,
said arming and dis-arming arrangement comprising means adapted to receive and respond
to a predetermined arming signal to arm the device and a predetermined dis-arming
signal to dis-arm the device, the arming and dis-arming signal being transmitted to
the device from a position remote from the device.
[0003] Preferably said arming and dis-arming arrangement is adapted to respond to an arming
signal comprising one or more pulses of ultrasonic sound and a dis-arming signal comprising
one or more pulses of ultrasonic sound.
[0004] Alternatively the arming and dis-arming is adapted to respond to an arming signal
comprising one or more pulses of electromagnetic radiation of a predetermined frequency
and dis-arming signal comprising one or more pulses of an electromagnetic radiation
of predetermined frequency.
[0005] Conveniently said pulse, when received by the arming and dis-arming arrangement are
passed through a filter so that only pulses of a predeter mined frequency are accepted.
[0006] Advantageously said arming and dis-arming arrangement incorporates a counter to receive
said pulses, the counter being adapted to execute a predetermined count and return
to zero, the counter advancing one count for each pulse received thereby, the arrangement
being such that the alarm device is armed when a predetermined count or counts are
present on the counter, and dis-armed when another count or counts are present on
the counter.
[0007] Conveniently an electric latch is provided to maintain actuation of the alarm signal
generator even if the said switch is re-opened after the switch has been closed to
actuate the alarm signal generator.
[0008] Preferably the device includes a key operated master switch.
[0009] Preferably the device is powered by means of a battery, a cover providing access
to the battery being normally locked in the closed position.
[0010] Conveniently the key utilised to actuate the key operated switch also actuates a
lock retaining the battery cover in position.
[0011] Preferably the alarm device is mounted within a housing provided with a hinged cover
or lid, the hinged cover or lid being adapted, when pressed towards the housing, to
depress a spring biassed plunger, to open said switch, the arrangement being such
that when the pressure applied to the cover or lid maintaining the cover or lid in
the closed position is released the plunger moves the cover or lid thus permitting
the switch to close.
[0012] Advantageously the device comprises means to emit a visible signal to indicate whether
the device is armed or not.
[0013] Preferably said light signal emitting means are actuated when the device is in the
unarmed condition.
[0014] The invention also relates to an alarm device as described above in combination with
an arming and dis-arming device adapted to generate said arming and disarming signals.
[0015] Preferably said arming and disarming device comprises a housing containing means
adapted to generate pulses of ultrasonic sound.
[0016] Conveniently the housing is additionally provided with a key adapted to actuate a
key operated switch on the alarm device.
[0017] In order that the invention may be more readily understood, and so that further features
thereof may be appreciated, the invention will now be described, by way of example,
with reference to the accompanying drawings in which:
FIGURE 1 is a perspective view of an alarm housing containing an alarm circuit;
FIGURE 2 is a perspective view of an arming and dis-arming device;
FIGURE 3 is a block circuit diagram of the circuitry contained within the arming and
dis-arming device; and
FIGURE 4 is a block circuit diagram of the alarm.
[0018] Referring initially to Figures 1 and 2 of the drawings an alarm arrangement in accordance
with the present invention consists of an alarm device 1 and an arming and dis-arming
device 2.
[0019] The alarm device 1 consists of an appropriate casing 2 provided with a slidable panel
3 which can be removed to permit a battery to be located in position within the housing.
A key operated switch 4 is provided to enable the device to be turned on and off.
The key operated switch also locks the battery cover in the closed position so that
when the device is switched on the battery cannot be removed. The housing 2 is provided
with a component 5, in the form of a hinged lid, which is movable relatively to the
rest of the housing. The component 5, when in the closed position, engages a spring
loaded plunger 6, which is associated with an appropriate switch as will be described
hereinafter, and thus, when the lid is in a closed position the plunger is depressed.
The plunger, however, is spring biassed and thus tends to force the lid 5 upwards.
The housing 2 has an ultrasonic receiver or transducer 7, a noise emitting transducer
or loud speaker 8, and an indicator lamp 9.
[0020] The arming and dis-arming device 2 consists of a tubular housing 10 formed of two
separate parts 11, 12 which are screw connected together and which thus present a
junction line 13. A battery may be inserted within the housing before the two housing
parts are screwed together. The housing part 11 has a key 14 mounted thereon. The
key operates the key operated switch 4. The housing part 12 is provided with an operating
push button 15 and an ultrasonic sound emitter 16.
[0021] When the illustrated device is to be utilised, the alarm device is switched on utilising
the key 14 in the key operated switch 4. Initially the device will be in a "safe"
condition and the indicating lamp 9 will thus be illuminated. The device may be packed
within a suitcase, briefcase or bag in such a way that the lid 5 is pressed firmly
downwardly against the upper surface of the housing 2, thus depressing the plunger
switch 6. When the suitcase is fully closed, the alarm device may be armed by using
the arming and dis-arming device to transmit, to the alarm device, a predetermined
ultrasonic signal. This may be done by pressing the button 15 on the arming device
2 a selected number of times, for example, six times. The arming device will thus
send six pulses of ultrasonic sound to the alarm device. If the suitcase or bag is
then opened by an unauthorised person, the lid 5 will move away from the housing 2
under the spring bias applied by the plunger 6. The alarm device will thus be activated,
and will emit a loud sound. Even if the cover 5 is pressed back down into position
so that the plunger 6 is again pushed down into the housing, the alarm will still
continue to sound until the battery has run out. It is not possible for a person without
the key 14 to switch off the device, or to remove the battery.
[0022] However, when an authorised person wishes to open the suitcase, the arming and dis-arming
device is again utilised, and the button 15 is again pressed a selected number of
times to send another predetermined ultra sonic frequency signal to the alarm device.
The number of times the button is pressed is such that the total number of depressions
of the button during the arming sequence and the dis-arming sequence is 20. The alarm
device will then again be in a "safe" condition, allowing the suitcase to be opened
without the alarm device emitting any noise.
[0023] Referring now to Figure 3 it can be seen that the circuit of the arming and dis-arming
device is relatively simple. The circuit includes a battery 17, and a switch 18, which
is actuated on depression of the push button 15, which effectively connects the battery
to the rest of the circuit components which comprise a tuned oscillator 19, the output
20 of which is fed to amplifier 21, the output 22 of which is connected to an ultrasonic
sound emitting transducer. The arrangement is such that whenever the switch 18 is
closed the oscillator generates a signal which is amplified and fed to the transducer
which consequently emits a pulse of ultrasonic sound.
[0024] The alarm circuit, shown in Figure 4, is more complex. The alarm circuit consists
of a battery 24, which can be connected to the rest of the circuit components by means
of the key operated switch 4. When the switch 4 is closed power is supplied to an
initial set of components which will now be described.
[0025] The initial set of components includes a transducer 25 adapted to receive the ultrasonic
sound generated by the arming and dis-arming device. The output 26 of the transducer
is connected to a frequency filter 27 which is tuned to the frequency of the oscillator
19. Thus the filter 27 only passes signals generated by the arming and dis-arming
device. The output 28 of the filter 27 is amplified by an amplifier 29 and passed
to a counting circuit 30. The counting circuit 30 is effectively a shift register
adapted to cycle through a count of 20. The shift register is associated with an indicator
which is constituted by the light emitting diode 9. The light emitting diode 9 is
illuminated whenever the count is zero, and thus when the alarm circuit is in a "safe"
condition.
[0026] A switch 31, activated by the plunger 6, connects the line energized by the key operated
switch 4 to a second set of components when the plunger 6 is not in the depressed
condition. The second set of components comprises a relay 32, which is controlled
by a signal from the counter 30 so that the relay 32 is closed whenever the count
in the counter is not zero. When the relay is closed further components are connected
to the battery 24.
[0027] The output of the relay which is energized when the relay is closed is fed through
a lead 33 to a node 34. The node is connected to an oscillator the output of which,
36 is connected to an amplifier 37 and thence to a sound emitting transducer or loudspeaker
38 (shown as loudspeaker 8 in Figure 1). When the switch 31 and the relay 32 are both
closed alarm device will thus emit a loud alarm signal. To prevent the signal being
terminated merely by depressing the plunger a further relay 39 is provided. The relay
39 is normally open. The relay 39 receiving power from a lead 40 regardless of whether
the switch 31 and/or the relay 32 are closed. The relay is adapted to close whenever
a voltage is present on the node 34, since this node is connected to the control terminal
of the relay by lead 41. The terminal of the relay 39 that becomes energized when
the relay is closed is connected, by lead 42, to the node 42. Thus the relay 39 acts
as a latch to maintain a voltage on the node 34, when such a voltage has been detected,
until the key operated switch 4 is opened.
[0028] When the alarm device is armed, as described above, initially the key 14 is used
to close the switch 4. The count in the counter is then zero, and the indicator lamp
9 lights up. The relay 31 will then be opened. The alarm device is then packed into
a suitcase with the lid 5 pressed downwardly so that the plunger 6 is depressed and
the switch 32 is in the opened condition. the arming device 2 is then utilised and
the push button 15 is pressed any number of times between 1 and 20 selected at the
whim of the person utilising the device. As the push button 15 is depressed so that
the switch 18 is closed and the arming circuit issues a series of pulses of ultrasonic
sound of a predetermined frequency. These pulses of sound are received by the transducer
25 and pass through the filter 27, then being amplified by the amplifier 29 and passing
to the counter 30. The count in the counter 30 thus advances. The indicator lamp 9
is extinguished, and the relay 31 is closed.
[0029] When the authorised person wishes to open the suitcase, he again utilises the arming
device, pressing the push button 15 an appropriate number of times so that the number
of pulses of ultrasonic sound issued by the arming device during the arming procedure
and the disarming procedure taken together is 20. These pulses of sound are again
received by the transducer 25 and passed through the filter 27 and the amplifier 29
to the counter 30. The count in the counter 30 is thus returned to zero. The indicator
lamp 9 is re-illuminated and the relay 31 is opened. It is then possible to open the
suitcase without the alarm device sounding.
[0030] If any unauthorised person attempts to open the suitcase, firstly they will not be
aware of the fact that the suitcase contains the alarm device. Secondly, even if they
suspect that the suitcase contains an alarm device of the described type, they will
not be aware of the precise pass frequency of the filter 27, and will thus have great
difficulty in determining if any particular ultrasonic frequency will or will not
be usable to advance the count present in the counter 30. Also the unauthorised person
does not know how many pulses have been used to set the count in the counter 30, and
thus the unauthorised person does not know how many additional pulses are required
to return the count in the counter 30 to zero.
[0031] When an unauthorised person opens the suitcase containing the described alarm device
when in the activated condition, the plunger 6 will push the cover 5 upwardly, thus
closing the switch 31. The oscillator 35, and the amplifier 37 will thus be connected
to the battery 24 and the signal generated by the oscillator 35 will be amplified
by the amplifier 37 and will be emitted as a loud screech by the transducer 38. Even
if the unauthorised person rapidly re-closes the suitcase, thus again depressing the
plunger 6 and opening the switch 31, the presence of the relay 39 ensures that the
oscillator 35 and the amplfiier 37 still receive power to enable the transducer 38
to emit the alarm signal.
[0032] If the described device is accidentally actuated by an authorised person, in other
words if the person using the device has not advanced the counter by a complete cycle
of 20 steps when the suitcase is opened, the alarm will sound, but the authorised
person may insert the key 14 in the key actuated switch 4, thus switching the device
off.
[0033] Whilst the invention has been described with reference to one particular embodiment
in which the counter is adapted to count up to 20 it is to be appreciated that the
counter may count up to any appropriate selected number.
[0034] Whilst the invention has been described with reference to an embodiment in which
the device is armed by means of an arming and dis-arming circuit which emits ultrasonic
sound pulses, it is to be appreciated that the alarm device may be activated in some
other way, for example by means of a radio transmitter or the like.
[0035] Also, whilst the described circuit includes relay devices, it is to be appreciated
that these relay devices may be constituted by transistor switches or the like.
[0036] The features as disclosed in the foregoing description, in the claims and/or in the
accompanying drawings may, both separately and in any combination thereof, be material
for realising the invention in diverse forms thereof.
1. An alarm device, said alarm device comprising a portable housing containing an
arming and dis-arming arrangement, and an alarm signal generator, and a switch, closure
of the switch serving to actuate the alarm signal generator when the device is armed,
the switch being adapted to be closed when part of the device on the exterior of the
housing is permitted to move away from the rest of the housing, said arming and dis-arming
arrangement comprising means adapted to receive and respond to a predetermined arming
signal to arm the device and a predetermined dis-arming signal to dis-arm the device,
the arming and dis-arming signal being transmitted to the device from a position remote
from the device.
2. An alarm device according to claim 1 wherein said arming and dis-arming arrangement
is adapted to respond to an arming signal comprising one or more pulses of ultrasonic
sound and a dis-arming signal comprising one or more pulses of ultrasonic sound.
3. An alarm device according to claim 1 wherein the arming and dis-arming arrangement
is adapted to respond to an arming signal comprising one or more pulses of electromagnetic
radiation of a predetermined frequency and a dis-arming signal comprising one or more
pulses of an electromagnetic radiation of predetermined frequency.
4. An alarm device according to claim 2 or claim 3 wherein said arming and dis-arming
arrangement incorporates a counter to receive said pulses, the counter being adapted
to execute a predetermined count and return to zero, the counter advancing one count
for each pulse received thereby, the arrangement being such that the alarm device
is armed when a predetermined count or counts are present on the counter, and dis-armed
when another count or counts are present on the counter.
5. An alarm device according to any one of the preceding claims wherein an electric
latch is provided to maintain actuation of the alarm signal generator even if the
said switch is re-opened after the switch has been closed to actuate the alarm signal
generator.
6. An alarm device according to any one of the preceding claims wherein the alarm
device is mounted within a housing provided with a hinged cover or lid, the hinged
cover or lid being adapted, when pressed towards the housing, to depress a spring
biassed plunger, to open said switch, the arrangement being such that when the pressure
applied to the cover or lid maintaining the cover or lid in the closed position is
released the plunger moves the cover or lid thus permitting the switch to close.
7. An alarm device according to any one of the preceding claims comprising means to
emit a visible signal to indicate whether the device is armed or not.
8. An alarm device according to any one of the preceding claims in combination with
an arming and dis-arming device adapted to generate said arming and disarming signals.
9. A combination according to claim 8 wherein said arming and dis-arming device comprises
a housing containing means adapted to generate pulses of ultrasonic sound.
10. A combination according to claim 9 wherein the housing is additionally provided
with a key adapted to actuate a key operated switch on the alarm device.