Note: Descriptions are shown in the official language in which they were submitted.
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A DETECT ION DEV ICE
T~IS I~VENTION relates to a detection device.
More particularly, the invention relates to a detection
device for detecting the occurrence of a predetermined
event.
According to the invention, there is provided
a detection device for detecting the occurrence of a
predetermined event, the detection device including ~ `
a transmitter means which transmits a transmitted ~-~
signal of a first characteristic and, upon the
occurrence of a predetermined event, causes a change in
the characteristic of the transmitted signal;
a receiver means arranged remote from the ~`~
transmitter means, the receiver means being responsive
to the tran,smitter means; and
a discernible alarm means connected to the receiver
means to be activated by the receiver means when the
receiver means receives the transmitted signal of ~ ;
changed characteristic or the receiver means fails to ;~ -
receive the transmitted signal. `
In this specification, the te~m i'a change in
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the characteristic of the transmltted signal" is to be
understood as including cessation of transmission of the
signal.
The device may include a detecting unlt to
which the transmitter means is connected, the sensing
means forming part of the detecting unit.
The detecting unit may further include a
signal generating means for generating the transmitted
signal. Then, the receiver means may include a
detection circuit for detecting the transmitted signal.
In a preferred embodiment of the invention,
the signal generating means is operable to generate a
series of pulses on a substantially continuous basis.
Then, the detection circuit may include a
missing pulse detector such that, in the absence of a
predetermined number of pulses in the transmitted
8ignal, the alarm means is activated by the receiving
means. In addition, the signal generating means may be
operable to generate, periodically, an identification
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code which is included in the transmitted signal.
Hence, it will be appreciated that, in use,
the transmitter means transmits a signal comprising a
string of pulses and, interspersed therein, the
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identification code. This signal is detec~ed by the
detection circuit of the receiving means and, while the
signal is being received, the receiving means remains in
a quiescent state and the alarm means is inactive.
The device may include a sensing means
connec~ed to the signal generating means. A particular
application of the invention is the detection of the
presence of liquid as defined below. In other words,
the occurrence of the event is the presence of liquid.
Then, the sensing means may detect the presence of the
liquid.
In this specification, unless the context
clearly indicates otherwise, the term "detecting the
presence of a liquid" is to be understood in a broad
sense as including the detection of flooding, the
detection of leaks oE liquids, the detection of the
falling into a body of water or other liquid of a person
or animal, or the like.
~.
When the sensing means senses the presence of
the liquid, a change of state of the sensing means
occurs and this, in turn, causes the signal generating
means to cease transmitting the pulses and the code.
Should the detection ci.rcuit of the receiver
means fail to detect a number of pulses within a
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predetermined period of time, the receiving means causes
the alarm means to be activated alerting a person in
control of the receiving means to the presence of water.
An example of this application of the
invention is the use thereof on a person or animal so
that should such a person or animal fall into a body of
water, another person is alerted thereto to enable
action to be taken. Thus, the sensing means and the
transmitter means (hereinafter referred to collectively
as the "transmitting section" for ease of refer~nce) are
arranged in a housing, the housing, in use, being worn
by the person or animal.
The transmitting section may thus include a
power supply, driven by a battery, the power supply
being incorporated within the housing.
The housing may, convenlently, include an
attaching means for attaching it to the person or
animal. The attaching means may thus include a switch
means via which the power supply is connected to the
battery. Typically, the attaching means may be a belt
or strap having a buckle for fastening in position on
the body of the person or animal. The switch means may
be incorporated within the buckle so that, in order for
the power supply to be activated, the buckle must be
closed to close the switch means.
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Further, the battery of the power supply may
be rechargeable. Thus, the detection device may include
a battery charging means for charging the battery.
Conveniently, the battery charging means may
be incorporated in a container containing the receiving
means. More particularly, the battery charging means or
circuit may be incorporated within a power supply
circuit of the receiving means.
To improve the versatility of the system, the
container may be portable and may have the alarm means
incorporated therein. In that case, the power supply
circuit of the receiving means may also incorporate a
battery supply.
In another embodiment of the invention, the
signal generating means may, in normal circumstances, be
inactive. Then, when the sensing means detects the
presence of the liquid, and changes state, the signal
generating means is activated to transmit a signal which
is received by the receiving means.
The invention is now described by way of
example with reference to the accompanying diagrammatic
drawings.
In the drawings,
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Figure 1 shows a schematic block diagram of a
detection device, in accordance with a first embodiment
of the invention, for detecting the occurrence of a
predetermined event;
Figure 2 shows a circuit diagram of a detecting
unit of the detection device of Figure 1; -:
Figure 3 shows a schematic block diagram of a
detection device, in accordance with a second embodiment
of the invention, for detectiny the occurrence of a ~.
predetermined event;
Figure 4 shows a circuit diagram of a detecting
unit of the detection device of Figure 3;
Figure 5 shows a circuit diagram of a transmitter
section of a detection device, in accordance with yet a
further embodiment of the invention, for detecting the
occurrence of a predetermined event; and
Figure 6 shows a circuit diagram of a receiver
section of the detection device in accordance with the
further embodiment of the invention.
Referring firstly to Figures 1 and 2 of the
drawings, a detection device, in accordance with a first
embodiment of the invention, for detecting the
occurrencs of a predetermined event, more particularly
the presence of a liquid and, specifically, water, is
illustrated and is designated generally by the reference
numeral 10. The detection device 10 is intended
particularly to be worn by persons who are non-swimmers
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or animals so that an alarm signal is given should such
a person or animal fall into a body of water such as a
swimming pool. The invention will be described with
reference to this application hereafter.
The detection device 10 comprises a detecting
unit 12 which is responsive to water, when water
impinges thereon, to emit a first signal. A transmitter
means or transmitter 14 is connected to the detecting
uni~ 12 and is responsive to said first signal to emit
a transmitted signal 16 upon receipt of the first signal
from the de~ecting unit 12.
The detection device 10 further includes a
receiver means or receiver 18 which is responsive to the
transmitted signal 16. The transmitter 14 and the
receiver 18 are matched so that only that transmltter 14
associated with the receiver 18 will cause the receiver
18 to be activated. It will, however, be appreciated -~
that, if desired, the detection device 10 could have a
plurality of transmitters 14 which are matched to a
particular receiver 18.
A discernible alarm means 20 is connected to
the receiver 18. The discernible alarm means 20
comprises an audible alarm device such as a buzzer 22
and a visual alarm device such as a light emitting
element 24.
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As described above, the detection device 10 is
intended particularly for use by non-swimmers. Thus,
the detecting unit 12 and the transmitter 14 are
contained in a housing 26 which can be worn in a
suitable fashion by such a person. Hence, for example,
the housing 26 could be worn watch-fashion by the
person, as a necklace, or the like.
The detecting uni~ 12 comprises a sensing
means 28 in the form of a pair of electrodes 30. The
electrodes 30 are spaced from each other to define a gap
between them. It will be appreciated that, when the gap
between the electrodes i5 bridged by water, a change in
resistance occurs. Hence, the electrodes 30 are
connected to a triggering device 32 which is triggered
when such a change in resistance occurs. The triggering
device 32 comprises a thyristor 34 with one of tha
electrodes 30 belng connected to a gate of the thyristor
34. An anode 38 of the thyristor 34 is connected to one
end of a coil ~0.1 of a switching means in the form of
a relay 40. The other e].ectrode 30 is connected to the
other end of the coil 40.1. The relay 40 comprises
normally open contacts 40.2 which are connected via
connections 42 to the transmitter 14.
A cathode 44 of the thyristor 34 is connected
to a variable potentlometer 46 whlch sets the
sensltivity of the detecting unlt 12.
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The detecting unit 12 is powered via a battery
48. A reset switch 50, which is a normally closed
switch, is connected in series with the battery 48.
In use, when a change of resistance occurs
between the e]ectrodes 30, such as when water impinges
on the electrodes 30, the thyristor 34 is triggered
causing current to flow in the coil 40.1 of the relay
40. When this occurs, the norma:Lly open contacts 40.2
close causing said first signal to be emitted to the
transmitter 14. This in turn causes the transmitted
signal 16 to be transmitted to the receiver 18, thereby
activating the receiver 18. Activation of the receiver
18, in turn, causes activation o the alarm means 20 to
alert a person to the fact that the wearer of the
housing 26 has fallen into a swimming pool. To reset
the device 10, the switch 50 is opened for a short
period and the electrodes 30 dried.
Referring now to Figures 3 and 4 of the
drawings, a detection device, in accordance with a
second embodiment of the invention, for detecting the
presence of water is illustrated. With reference to
Figures 1 and 2 of the drawings, like reference numerals
refer to like parts, unless otherwise specified.
In this embodiment of the invention, the ; `~
contacts 40.2 of the relay 40 are normally closed ~ ~
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contacts. Hence, the contacts 40.2 of the relay 40
remain closed and a first signal is sent along
connections 42 to the transmitter 14. The transmitted
signal 16 is in the form of a string of pulses. While
the transmitter 14 is receiving the first signal from
the detecting unit 12, the string of pulses 16 is
emitted by the transmitter 14 to be received by the
receiver.
The receiver 18 has a detection circuit 52
incorporated therein. While the string of pulses 16 is
being received by the receiver 13, the receiver 18 is in
a quiescent state and the alarm means 20 is inactive.
If a pulse is not received by the missing pulse detector
52 within a predetermlned period of time, the missing
pulse detector 52 causes the receiver 18 to activate the
alarm means 20.
Thus, in this embodiment of the invention,
when water i.mpinges on the electrodes, the thyristor 34
is triggered causi.ng current to flow in the coil 40.1 of
the relay 40. When this occurs, the contacts 40.2 of
the relay 40 open thereby causing cessation of the
signal from the detecting unit 12 to the transmitter 14.
This in turn causes the transmitter 14 to cease emitting
the string of pulses 16. The absence of the pulses 16
is detected by the missing pulse detector 52 causing the
receiver 18 to activate the alarm means 20. Activation
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of the alarm means 20 alerts a person to the fact that
the wearer of the housing 26 has fallen into the
swimming pool.
Referring now to Figures 5 and 6 of the
drawings, a transmitter section and a receiver section,
respectively, of a detection device in accordance with
yet a further embodiment of the invention is
illustrated. Once again, with refPrence to the previous ~ -
drawings, like reference numerals refer to like parts,
unless otherwise specified.
: ,:
The transmitter section, which is designated
generally by the reference numeral 60, comprises the .
transmitter 14, the sensing means 28 comprising the pair
of electrodes 30 and the detecting unit 12.
:
In this embodiment of the invention, the
detecting unit 12 is a solid state device. Typically,
the detecting unit 12 comprises an embedded micro-
controller PROM chip 62. The chip 62 is programmed to
transmit a series of pulses through the transmitter 14
every few seconds. After a predetermined number of
pulses have been sent a timer of the chip 62 initiates
the transmission of a unique identification signal via
the transmitter 14. The identification code emitted by
the chip 62 is governed by a series of inputs in the
form of switches 64 to the chip 62.
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The transmitter section 14 includes a
stabiliser in the form of a surface acoustic wave
resonator 66 for smoothing oscillations of a transistor
68 driving an antenna loop 67 of the transmitter 14.
The resonator 66 also serves to reduce frequency drift
of the transmitter 14.
As indicated above, the transmi~ter section 60
is self-contained within the housing 26 and includes a
power supply 70. The power supply 70 is driven via a
bat~ery which is received in a battery compartment 72.
The power supply provides an unregulated 12 volt output
74 and, via a regulator 76, a regulated 5 volt output
78. :
The battery used in the transmitter section 60
is a re-chargeable battery.
A switch 80 is located between the battery
compartment 72 and the outputs 74 and 78. ~he switch 80
is a normally open switch and is closed when buckles of
a strap (not shown) carrying the housing 26 are closed,
in use.
Referring now to Figure 6 of the drawings, the
receiver section of the detection device 10 is
illustrated and is designated generally by the reference
numeral 90. The receiver section 90 incorporates the
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receiver 18, the alarm means 20 and a power supp].y
circuit 92.
The receiver 18 also comprises an embedded
micro-controller PROM chip 94. The chip 94 is similarly
configured to the chip 62 of the detecting unit 12. The
chip 94 is responsive to the same code as that of the
chip 62 via a set of slmilarly configured switches 96.
Thus, the chip 94 of the receiver 18 is responsive to
the series of pulses and the identification code emitted
by the chip 62 of the detecting unit 12 and which is
transmitted via the transmitter 14.
In this embodiment of the invention, the alarm
means 20 comprises a buzzer 98 driven via a dxive
transistor 100 and an lndicating means 102 driven by a
transistor 104.
The indicating means 102 is in the form of a
light emitting diode (LED). The LED 102 is connected
via the transistor 104 to an output of the chip 94 and
is operable, when the detection device 10 is operational
2G to flash while the signal is being received so that a
person can ascertain that the detection device 10 is
operating. In addition, if desired by closing a switch
106, the buzzer can be caused to emit a low intensity
sound while the receiver 18 is receiving signals from
the transmitter 14.
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The power supply circult 92 of the receiving
section 90 comprises a battery charging circuit 108.
The battery charging circuit 108 is used for charglng a
battery of the transmitter section 60. Thus,
conveniently, a container, represented schematically by
line 110 containing the receiver section 90 may have a
seat defining formation therein in which the transmitter
section 60 is receivable. A set of contacts 112,
engaged by the battery of the transmitter section 60,
may be arranged in the seat defining formation of the
container 110. Hence, it will be appreciated that, when
the detection device 10 not in use, the transmitter
section 60 is placed in the seat defining formation of
the housing of the container 110 to enable a battery of
the transmitter section 60 to be re-charged.
Conveniently, the container 110 can also be
portable. To cater for this, the power supply circuit `
also includes a battery 114. The power suppl~ circuit
92 includes a battery monitoring circuit 116 for ~:
monitoring the condition of the battery 114. When the
voltage of the battery 114 drops below a predetermined,
threshold value, an appropriate signal is sent along ~ :
line 118 to the chip 94 to cause the alarm 20 to be
activated.
Once again, with this embodiment of the
invention, should the sensing means 28 detect the
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presence of water, a change of resistance occurs across
the electrodes 30 causing the appropriate signal to be
input into the chip 62 of the detecting unit 12. When
this occurs, the chip 62 ceases the transmission of the
pulses and the code. When this occurs, the chip 94 of
the receiver 18, or if it failed to detect pulses for a
predetermined period of time, causes a signal to be
output to activate the alarm 20. The buzzer 98 is
activated alerting the person in control of the receiver
section 90 of the device 10.
A further advantage of the two latter
embodiments of the invention is that it serves to assist
a person to keep a check on another person. Thus, for
example, a mother can keep a check on her toddler by ~ ~ :
attaching the housing 26 to the toddler. Then, if the ~ .
toddler moves out of range of the receiver 18, this will
cause the receiver to activate the alarm means 20. It
will be appreciated that this is also especially
advantageous for use by infirm people or people of .
reduced mental capacity.
Hence, with the provision of the detection
device 10 in accordance with the invention, rapid ;
remedial actions is facilitated where a non-swimmer or
animal has fallen into a body of water or person moves
out of range of the receiver 18.
