Note: Descriptions are shown in the official language in which they were submitted.
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W~RNING LIG~T SYSTEM FOR USE WITH A SMOKE DETECTOR
The present invention relates to a smoke detector/warning
light system, and more particularly, to a device that includes a
light source for mounting in a window or at some other highly
visible location near where a smoke alarm is located so that if
the smoke alarm activates due to detecting smoke or fire and
produces audible signals, the light source will activate and
produce light flashes to call attention to a room or rooms where
persons may be located, hopefully so that a timely rescue can be
undertaken. The present invention is especially useful as an aid
in locating children, disabled persons and others in a building
who may not be able to understand the need or be able to exit the
building or may require assistance to e~it.
Generally, a user of the device will place it in a
room where there is a smoke detector and where potential fire
victims are located, such as a room where a child is sleeping, so
that when the smoke detector emits an audible signal, the audible
signal will activate a circuit associated with a light source of
the preseht device to cause the light to begin to flash to let
outsiders know where the dangers areand the most likely place
where there are potential victims that may need help. The device
can also be located where there are other items of value that need
to be rescued. It can therefore be understood that the present
device provides means to give a warning that is intended to
identify where there is need for help in order to reduce the time
required to get a rescue operation started.
Many devices have been constructed to alert occupants of a
home or other building when smoke is detected and to give warning
of such. Some of these have included well known smoke detector
devices which are usually battery operated and when activated by
2002651.
smoke or fire, produce an easily recognizable alarm noise intended
to alert persons who hear the noise of the dangerous condition
that has been detected. There are also such devices which
activate a light producing device to give a visual alarm.
One known form of such a smoke alarm warning device is
disclosed in Skarman et al U.S. Patent No. 4,570,155. This patent
discloses a device that includes a portable light source for
producing emergency illumination of hallways and similar exit
areas when a main power supply fails such as during a fire. The
Skarman et al device includes a strobe circuit which periodically
activates a detection circuit which responds accordingly to an
occurrence of an audio smoke detector signal. Other known prior
art devices of some interest are disclosed in Todd U.S. Patent No.
4,524,304 and Scott et al U.S. Patent No. 4,25~,291. Neither of
these patents disclose a system which not only alerts people to
the presence of smoke or fire, but also provides a visible
flashing warning which can be seen from outside the building where
the smoke detector is located and which identifies a room or rooms
where danger e~ists so that rescuers will know where first to go.
The present invention fulfills this need in a novel and efficient
manner and by means which include novel circuit means that are
maintained in a continuous ready condition.
The present invention achieves these and other objectives in
a system which continuously applies power to a light source
activation circuit, which circuit also includes means that
responds to audio noise or other signals produced by a smoke
detector. When a smoke detector produces an audible noise signal,
a light source suitably placed to identify a room or rooms where
danger most likely e~ists is energized to produce a flashing light
for quick room identification. The flashing light source should
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be bright enough to draw attention to it so that rescuers and
others will know which areas to search first. When more than one
of the present flashing light devices are used in the same home or
building, it is possible to have a smoke detector device activate
one or more flashing light devices. This can be done by including
radio frequency transmitting means in the smoke detector. In this
case an antenna would be installed on the alarm device instead of
having microphones and the RF signals would be applied to the
amplifier instead of output of the microphone. Thus, when the
smoke detector activates, it will emit radio signals along with
the audio signals which can be received by all the flashing light
devices to cause them to activate.
Typically, the flashing light source will be mounted on or
near an outside window or at some other highly visible place, and
the smoke detector will be mounted near enough to the flashing
light source and its associated circuit so that there is little or
no chance that the circuit will not be able to respond to an
audible smolce detector signal. Although it is contemplated to
have the f~lashing light and its associated detection circuit
constructed as separate units for mounting apart from each other,
possibly even in different rooms under some circumstances, it is
also contemplated and in most cases it is preferred to have the
light source and its circuit combined in a common housing. The
important thing is that the circuit for the flashing light be
located so as to be able to respond to and be activated by audible
signals produced by the smoke detector and so that its operaton
does not depend on any other signal or circuit condition to be
activated. By so providing, the chances for failure are greatly
reduced.
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The present invention which resides mainly in the circuit
for the light source has its own power source, such as an
ine~pensive nine volt battery, which circuit, when not responding
to a smoke detector signal, continuously supplies a small trickle
of energy to the light activation and signal detection circuit,
usually to an operational amplifier (Op-Amp) circuit which is
thereby maintained in a ready condition. The amplifier circuit
typically draws a small amount of current, in the range from about
two to five microamperes, which is not enough to represent a
substantial drain on the battery except over a very long time
period such as a year or longer.
By providing this small trickle of charge constantly to the
amplifier circuit, the amplifier is kept in a constantly ready
condition and this is an important and significant advantage in
that it maintains the circuit so that as soon as the smoke
detector activates, the audible signal produced will cause the
flashing light also to activate without delay and without
requiring periodic circuit testing. This also means that only one
condition,~namely detection of activation of a smoke detector,
need take place for the flashing light alarm to commence
flashing. This, in turn, means that the light source will start
to 1ash sooner after smoke is detected than would be the case
with known devices such as those discussed above.
With the present device, the input of the Op-Amp generally
is connected through a filter circuit to the output of a
microphone which responds to audio signals produced by a smoke
detector, and the amplifier produces an output whenever the
microphone senses such a signal. The output of the amplifier is
connected to the input of a bandpass filter designed to pass
signals having a frequency within some predetermined range. The
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outputs of the bandpass filter are applied as inputs to a
detector circuit which converts the alternating filter outputs
to a direct current (d.c.) signal which is used to activate or
close a switching device. When the switch is closed, it
completes a circ~it between a timer circuit, a power source
and a light source, which causes the light source to flash.
The timer circuit controls the flashing rate or frequency of
the light source.
As soon as the smoke detector is activated by smoke, the
light source of the present device will immediately commence
flashing to indicate to outsiders including potential rescuers
which room or rooms are the ones where help is needed. These
are the rooms where there are children, disabled persons or
others in need of help. The present device may optionally
also include an on-off switch connected into the circuit
between the power source and amplifier to enable the user to
control when power is to be supplied to the circuit. This can
be done to save battery power when the room is not occupied
and enables the user to turn the device off when the reasons
for using it no longer exist.
Accordingly the present invention seeks to provide novel
means to energize a light source in response to an audio or
other noise signal including also a radio frequency signal
produced by a smoke detector.
The invention in one broad claimed aspect provides a
warning system for alerting a rescuer in the vicinity of a
building of an emergency condition in the building and for
indicating which opening of the building the rescuer should
enter first. The system comprises a physically separate and
distinct detector, the detector including an emergency
condition sensing and signalling device for sensing smoke or
fire in proximity of the detector and for signalling an
emergency condition when smoke or fire is sensed and a
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physically separate and distinct alarm device, the alarm
device including sensing means for sensing the emergency
condition signal generated by the emergency condition sensing
device in the building. An amplifier receives and amplifies
the emergency condition signal after the signal is sensed by
the sensing means and for producing an output signal and
generating means is responsive to the output signal received
from the amplifier for generating an intermittent light beam
signal. Preventing means is coupled between the amplifier and
the generating means for preventing false signals from
activating the light beam generating means, the preventing
means including a bandpass filter. Ensuring means is coupled
between the amplifier and the generating means for ensuring
that only emergency condition signals are supplied to the
light beam generating means, the ensuring means including a
low pass filter. Mounting means is provided for mounting the
device proximate to the building opening in a position to emit
the intermittent light beam signal so it can be seen from
outside the building.
The invention in another aspect pertains to a warning
device responsive to emergency condition signals and having an
input sensing circuit having an input and an output and an
output circuit including a switching device and having an
input and an output. The improvement in the device comprises
means for filtering out false signals and for ensuring the
actuation of the warning device upon receiving bona fide
emergency, condition signals, the filtering means including an
operational amplifier having an input coupled to the output of
the input sensing circuit and an output, a bandpass filter
having an output and an input coupled to the output of the
operational amplifier for passing signals having a frequency
within a predetermined range, a detector circuit having an
output and an input coupled to the output of the bandpass
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filter for converting the passed signals into a direct current
and a low pass filter coupled to the output of the detector
circuit and to the input of the output circuit for passing to
the output circuit only those signals which are of sufficient
magnitude and which are present for a long enough duration to
allow them to pass through the low pass filter to the output
of the switching device to activate the switching device.
Still further the invention pertains to a warning system
for alerting a rescuer in the vicinity of a building of an
emergency condition in the building and for indicating which
one of several openings to the building the rescuer should
enter first, the improvement comprising a physically separate
and distinct alarm device positioned in close proximity to an
emergency sensing and signalling detector, the alarm device
including sensing means for sensing an emergency condition
signal generated by the emergency condition sensing and
signalling detector, an amplifier coupled to an output of the
sensing means for amplifying the emergency condition signal
after the signal is sensed by the sensing means and a timer
circuit and a light source, for generating an intermittent
light beam signal. A bandpass filter is provided for passing
signals having a frequency within a predetermined frequency
range of the amplified emergency condition signal and a
detector circuit rectifies the passed emergency condition
signal and includes a low pass filter for passing signals
having a predetermined amplitude level coupled in series
between the output of the sensing means and an input of the
timer circuit. The sensing means, the bandpass filter, the
detector circuit and the low pass filter are coupled in series
and mounting means is provided for mounting the alarm device
proximate to one of the building openings in position to emit
the intermittent light beam signal so the intermittent light
beam signal can be seen from outside the building.
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2002651
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These and other aspects and advantages of the presentinvention will become apparent to those skilled in the art
after considering the following detailed specification of a
preferred embodiment in conjunction with the accompanying
drawings.
Brief Description Of The Drawinqs
Fig. I is a perspective view of a part of a room
equipped with an alarm system including a smoke detector and
one embodiment of the present flashing alarm constructed
according to the present invention;
Fig. lA is a fragmentary view from outside of a window
pane having the flashing alarm mounted thereon;
Fig. 2 is a block diagram of the circuit for the alarm
producing portion of the system of Fig. 1, an alternate
embodiment shown in dotted outline; and
Fig. 3 is a schematic circuit diagram showing in more
detail the circuit of Fig. 2.
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20026Sl
~- Detailed Description Of The Invention
~ eferring to the drawings more particularly by reference
numbers wherein like numbers refer to like components, Fig. 1
shows a portion of a room equipped with an alarm system 10
constructed according to the present invention. The alarm system
10 includes a smoke detector 12 which may be of conventional
construction and is capable, when smoke or fire is detected, of
producing an easily recognizabie audio signal, usually of
relatively high frequency. Such signals are usually irritating
noise signals intended to attract attention and action. The smoke
detector is shown installed on the ceiling usually at a central
location in the room although any convenient location can be used.
The system 10 also includes a flashing alarm portion 14
which is shown mounted on or adjacent to a window, preferably an
external window. The alarm 14 has a light bulb 16 mounted thereon
or therein in position to produce visable light outside the room
whenever it is energized. The alarm 14 can be mounted on a window
1~ such as by being attached to window pane 20 using one or more
suction cup devices 21, as shown in Fig. lA, or it can be attached
or mounted in some other way as by being attached to the window
frame 22 or jamb 24 using threaded fastener means or the like.
The device could even be suspended on a cord or wire from the
upper frame member 26, if desired. The important thing is that
the bulb 16 be visible from outside the room and that the alarm be
located in close enough pro~imity to the smoke detector 12 to be
able to respond to the noise signals produced thereby. It is also
comtemplated to mount the smoke detector in the same housing as
the alarm although this is usually not preferred unless the device
can be located in an area where the presence of fire or smoke is
best detected.
200Z651.
~ ig. 2 is a block diagram of the circuit 30 for the flashing
alarm portion 14 of the present system. The circuit includes a
microphone 32 capable of responding to the noise signals produced
by the smoke detector 12. The microphone 32 produces outputs
which are applied to the input of an amplifier circuit through a
filter circuit, shown as operational amplifier 34 (Op-Amp), which
has a power input connection 36 to a battery 38. This power
connection is important because it means the amplifier 34 will be
maintained in a constantly ready condition. The amplifier 34 and
the battery 38 also have ground connections as shown. The output
40 of the amplifier 34 is connected to a band pass filter circuit
42 which has its output connected to a detector circuit 44 which
in turn is connected to a low pass filter circuit 46. The output
of the low pass filter circuit 46 is connected to a control
electrode or gate 48 of a switching device 50 which may be an
electronic switching device such as a MOSFET, an SCR or some other
like switching device.
The switch 50 is connected in series with a timer circuit 52
and the battery 38. The timer 52 is in turn connected to ground
througll the ligllt source 16. The frequency of the timer circuit
52 depends on the time constant thereof. The time constant should
be selected to produce a light flashing rate that attracts
attention and indicates an emergency, the idea being to produce a
suitable warning that will attract rescuers or persons who can
offer or seek help.
It is important to the operation of the present system as
indicated that the Op-Amp circuit 34 receive a constant trickle of
current from the battery 38 so that it is maintained in a constant
ready condition. This means that whenever the microphone 32
responds to a smoke detector noise signal, the amplifier will
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~rmmediately produce an output to cause the switching circuit 50 to
close and to thereby activate the timer 52 to cause the light 16
to flash on and off. The timer, not the switch, flashes the light
16 but the timer is only able to flash the light when the switch
50 is closed. This is to be contrasted with other circuits which
require several different things to take place before an alarm
condition can be produced. This also means that with the present
system there is less that can go wrong to cause a failure while at
the same time the circuit in standby condition draws relatively
little current and hence can operate for a very long time even a
year or longer without losing power.
Many variations of the block diagram circuit showrl in Fig. 2
are possible and contemplated. For example, the amplifier 34
could be integrated into the microphone 32, in which case power
could be supplied directly to the microphone 32. Another
possibility, as aoresaid, is to include a radio transmitter in
the smoke detector and receiver means including an antenna such as
antenna 54 (~ig. 2) in the flashinq light unit so that if the
smoke dete~ctor activates, it will transmit radio frequency signals
that can be received by any alarm device in range thereof. The
receiver means would operate the circuit in a manner similar to
the microphone by causing the switch 48 to close and activate the
circuit of the timer 52 and the light bulb 16. One advantage of
using RF transmissions is that it may substantially increase the
range that can be used between the smoke detector and the alarm
device. In fact, they may even be located in different rooms.
Fig. 3 shows more circuit details of the present device
including showing the microphone 32 (or antenna 54) connected to
an amplifier input circuit which includes a sensitivity control
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~rotentiometer 60, and an input filter circuit formed of capacitors
62 and G~ and resistors 66 and 68 connected as shown. ~nother
capacitor 70 for the band pass filter 42 has its output side
connected to the detector circuit 44 formed by diodes 72 and 74.
The output side of the detector 44 is connected to the low pass
filter g6 formed of capacitors 76 and 78 and resistor 80. The
output of the filter 46 is connected to the gate or base electrode
48 of the MOSFET ~0.
The timer circuit 52 includes a timer device 82 connected to
resistors ~ and 86 and capacitor 88 as shown. The light 16 is
also connected between the power source or battery 38 and the
output 90 of the timer device 82. The timer device 82 may be in
. . .
the form of an integrated circuit which operates in conjunction
with the resistors 84 and 86 and the capacitor 88 as a stable
multivibrator or flasher circuit. Since the MOSFET 50 is in the
power supply path of the flasher or timer circuit 52, the light 16
can only be energized to flash when the MOSFET 50 is on or
closed. This can only occur when an audible signal of a frequency
that matc~es the frequency range of the band pass filter 42 is
present and is of sufficient magnitude to reach the trigger
potential of the MOSFET. The signal must be present for a long
. . .
enough duration to allow the low pass filter 46 to pass it on to
the MOSFET.
As indicated above only the amplifier circuit 34 and the
timer or flasher circuit 52 drawing power or are able to draw
power from the battery 38, the amplifier circuit 34 drawing power
continuously and the timer circuit 52 drawing power only when a
smoke detector signal is detected. The purpose of the Op-Amp
circuit 34 is to amplify the signals it receives, which are
relatively small signals produced by the microphone 32 or in the
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tenna 5~, to a level suficient to make the detector circuit
activate the MOSFET switching circuit 50. If the MOSFET is in its
conducting condition it will ground the timer circuit 52. The
timer circuit 52, as stated, is connected to the power source and
when the MOSFET 50 conducts, power is supplied to the lamp 16
under control of the timer circuit 52. The timer circuit operates
to cause the lamp to flash on and off to provide the desired
warning. Thus, it can be seen that once an audible signal is
detected by the microphone, the amplifier and the associated
circuitry determines whether the signal is within a proper
acceptable frequency range, and if it is, converts the signal to
direct current (d.c.) and utilizes the signal to activate the
lamp. By minimizing the time between when the smoke detector
signal is detected and when the lamp begins to flash, it allows
faster and hopeully, earlier identification of rooms in which
persons, such as small children, may be located, and this may
result in the saving of life.
The use of a crystal microphone capable of responding to
audible s~gnals even over a fairly great distance is preferred and
the magnitude of responses that are sufficient to cause an alarm
condition is controlled by the setting of the potentiometer 60.
The potentiometer 60 therefore allows the sensitivity of the
system to be adjusted as desired. The capacitors 62 and 64 and
the resistors 66 and 6~ in conjunction with potentiometer 60 and
the amplifier 34 provide a bandpass filtering function which
eliminates responses that are not in the desired frequency range.
This feature reduces the likelihood of false alarms. A desired
amplifier for this purpose is a simple voltage Op-Amp having a
constant gain factor. For example, a gain factor of 1000, means
that a 1 millivolt rms input from the microphone 32 will appear as
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~-1000 millivolt (or 1 volt) rms signal. The other amplifier
connections provide a ground reference and a power connection.
Importantly, as stated, with the connections as shown, some amount
of power is always provided to the amplifier 34 from the power
source. ~lso, as stated, the Op-Amp 34 typically will draw
between about 2 to 5 microamperes when in standby, and this amount
of power will not adversely effect the power source except over a
very long time period.
It is anticipated that the circuits shown in Figs. 2 and 3
will be mounted on a printed circuit board using circuit
construction and connection techniques well known in the art. A
manual switch 94 may be provided to cut off all battery power to
conserve energy when there is no reason to operate the device.
Thus, there has been shown and described a novel warning
light system for use with smoke detectors and the like which
fulfills all of the objects and advantages sought therefor. It
will be apparent to those skilled in the art, however, that many
changes, modifications, variations and other uses and applications
for the su~ject device are possible and contemplated, and all such
changes, modifications, variations and other uses and applications
which do not depart from the spirit and scope of the invention are
deemed to be covered by the invention which is limited only by the
claims which follow.
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