Note: Descriptions are shown in the official language in which they were submitted.
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SMOKE ALARM TEST REMINDER DEVICE
BACKGROUND OF THE INVENTION
The advantages of having one or more working smoke alarms in a home are well
documented. Countless
lives are saved every year by working smoke alarms, because people are able to
escape from a fire when
given adequate waming. However, many lives are lost every year due to fire in
homes equipped with smoke
alarms, because those smoke alarms did not work when needed. That is evidence
that many people never
test their smoke alarms or, if they do, they do so rarely.
According to statistics from the National Fire Protection Association (NFPA),
the US Fire Agency (part of
FEMA) and the US Consumer Protection Association:
= There are 3,000 - 5,000 civilian fatalities due to fires in the US every
year.
= There are 15,000 - 20,000 civilian injuries due to fires in the US every
year.
= Approx. 80% of fire deaths occur in the home.
= Approximately 20-30% of smoke alarms in homes do not work.
There is also strong evidence to suggest that when people, especially
children, take part in the monthly
testing of smoke alarms, they are more likely to associate the smoke alarm
sound with the smoke alarm
itself. This increases the likelihood that they will respond positively to the
smoke alarm when a real fire
occurs.
All agencies in Canada and the United States that are tasked with educating
the public about fire safety
support the NFPA recommendation that residential smoke alarms be tested and
inspected once per month.
All smoke alarms advertised or sold in Canada must meet specifications
developed by the Underwriter's
Laboratory of Canada (ULC). In the US, similar specifications are developed by
the NFPA and by the
Underwriter's Laboratory. Every smoke alarm now sold in North America has a
test button that, when
pressed, causes its alarm to sound. These alarm tones must meet strict
specifications for frequency,
repetition rate and sound pressure level (i.e. 'loudness').
Given the statistics presented above, it is apparent that, if more residential
smoke alarms were tested
regularly, there would likely be fewer fatalities and injuries due to fires
(assuming that non-working smoke
alarms were made to work again). It is also apparent that people are not
testing their smoke alarms regularly.
Presently, there is no device available whose sole purpose is to remind people
to regularly test and inspect
their smoke alarms.
This invention provides a novel reminder device whose sole purpose is to
remind people to inspect and test
their smoke alarms regularly. This reminder device is self-contained and
compact, so it can easily be
mounted in many possible locations and on many different surfaces. This
reminder device utilizes a visual
indicator to provide the reminder, but an optional audible indicator can also
be used. To increase the
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probability that its indicator(s) will be seen/heard, such a reminder device
must be situated in a well-travelled
area of the house. Since one of the most highly travelled areas in a house is
the kitchen, this reminder
device can be packaged as a 'fridge magnet' assembly. However, many other
packaging and mounting
configurations are also possible, and the reminder device may be packaged
within or as part of another
device or object that performs a completely different purpose.
The reminder device's operation is very simple. At regular time intervals
(typically 30 days), the device's
internal timer expires, and its visual and/or audible indicators activate.
This provides the reminder to test and
inspect all smoke alarms. The user then manually resets the device, which
deactivates the indicator(s) and
restarts the timer for another reminder interval.
To encourage children to take part in the monthly testing of smoke alarms,
this reminder device optionally
includes an 'audio reset' feature. The device optionally includes an audio
detector that will automatically
reset the device when it detects the alarm tones from a smoke alarm being
tested. The general idea is that,
once the indicator(s) on the reminder device activate, the child sees or hears
them and reminds an adult it is
time to test the smoke alarms. The child is encouraged to assist the adult by
holding the reminder device up
close to the first smoke alarm while the adult presses the smoke alarm's test
button. When the reminder
device detects the alarm tones from the smoke alarm, it resets itself, and its
indicator(s) turn off. All
remaining smoke alarms should then also be tested and inspected.
The reminder device is primarily intended to be powered by a DC battery, and
is simple enough that it can be
designed using very low-power electronics and a high capacity battery in order
to maximize the time between
battery replacements. Depending on the packaging, the reminder device could
also be powered by AC
voltage with a DC battery backup.
PRIOR ART
US patent no. 5,568,129 (Sisselman, Oct 96) describes an alarm device
including a self-test reminder circuit.
Since the reminder circuit in that invention is intearal to the alarm device,
the reminder circuit will not perform
its function if the alarm device malfunctions or loses all electrical power
(including battery power). As the
statistics presented earlier show, a significant percentage of smoke alarms
fail to work - and the purpose of
testing smoke alarms is to identify those that do not work. Integrating the
reminder circuit into a smoke alarm
that has dead batteries or is defective defeats the purpose of the reminder
circuit. Also, since most smoke
alarms are mounted to ceilings, high up on walls, or in other out-of-the-way
locations, it is less likely that this
device's reminder indicators would be seen or heard.
SUMMARY OF THE INVENTION
In the drawings, which form a part of this specification,
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Fig. 1 is a block diagram showing one embodiment of the invention;
Fig. 2 is a block diagram showing one possible embodiment of the Timer shown
in Fig. 1;
Fig. 3 is a block diagram showing one possible embodiment of the optional
Audio Detector shown in Fig. 1;
Fig. 4 is front, side and rear views showing one embodiment of the invention
packaged as a battery-powered
'fridge magnet' reminder device.
DETAILED DESCRIPTION OF THE INVENTION
Fig. 1 provides an overall block diagram for the reminder device. When power
is applied to the device, the
timer I is activated. When the timer expires (typically 30 days), its latched
output activates the visual
indicator 2 and/or the optional audible indicator 3, and enables the optional
audio detector 4. In this
embodiment, the visual indicator 2 is a flashing bright LED. The optional
audible indicator 3 could be a
piezoelectric buzzer, beeper or other similar component.
Once enabled, the optional audio detector 4 samples the audio input signal
from the audio transducer 5.
When this detector detects alarm tones from a smoke alarm being tested, it
generates a reset signal. This
reset signal resets the timer 1, which in tum causes the optional audio
detector 4 to be disabled. A
momentary pushbutton 6 provides for a manual reset of the reminder device for
situations where:
= The user chooses to reset the device manually (i.e. does not wish to utilize
the audio reset feature), or
= The device is not manufactured with the optional audio detector.
There are several possible configurations for the voltage source 7, depending
on how the reminder device is
packaged:
= DC battery. A compact DC battery provides enough electrical power to operate
the device for an
extended period of time (e.g. one year or more). Since there are some battery-
powered smoke alarms
now available that will operate for 10 years from a single battery, it would
be advantageous for this
device to be able to run for 10 years from a single battery as well.
= AC power with DC battery backup. The device would operate primarily from AC
power, and switch to
battery power whenever AC power is lost. One variation of this configuration
is that the AC power could
also be used to recharge the DC backup battery.
Fig. 2 provides details on one possible embodiment of the timer 1, using
standard digital logic components.
The output from oscillator 8 is fed into a divide-by-N counter 9 to extend the
oscillator's period to the
reminder interval (typically 30 days). When this counter counts up to the
reminder interval, its output is fed
into latch 10. The output of latch 10 becomes the enable signal that activates
visual and/or audible indicators
(2 and 3). Counter 9 and latch 10 are reset by the reset signal provided by
the manual reset button 6 or
audio detector 4. Oscillator 8 could be a standard 555 timer configured to run
in astable mode.
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Many combinations of oscillator frequency and divide-by-N counter size are
possible to provide the desired
reminder interval (typically 30 days). If the 'N-size' needed is larger than
is available on a single counter,
multiple divide-by-N counters can be cascaded together. The following table
describes several possible
combinations of oscillator and counter N-size. This table is based on
2,590,000 seconds in a month (60
secimin x 60 min/hour x 24 hours/day x 30 days/month). Since binary divide-by-
N counters are very
common, the last column in this table shows the approximate number of bits
needed to realize each N-size.
Oscillator Oscillator N-size Size of binary counter
Frequency (Hz) Period (sec) (bits)
0.1 25,900,000 24-25
1 1 2,590,000 21-22
0.1 10 259,000 18
10 Fig. 3 provides a conceptual description of the optional audio detector,
which, in a preferred embodiment, is
only enabled after the reminder period has expired. The input signal from the
piezoelectric audio transducer
5 is sampled using three different stages:
1. A bandpass filter 11, with lower and upper cut-off frequencies set based on
the NFPA specifications for
smoke alarms (approx. 3000-4000 Hz). This filter reduces the possibility that
the device will reset due to
audio signals from other devices commonly found in the home.
2. A threshold detector 12. The Underwriters Laboratory (UL) voluntary
standard, UL 217 - Single and
Multiple Station Smoke Alarms, specifies that a smoke alarm must emit an alarm
signal with an A-
weighted sound pressure level of at least 85 decibels (dBA) at a distance of
10 feet. This threshold
detector is designed to only pass an audio signal with at least this sound
pressure level [implying that the
user must hold the reminder device within approximately 10 feet of the smoke
alarm being tested].
3. A counter 13. This counter ensures that multiple alarm tones are received
from a smoke alarm being
tested. UL 217, section 34.3, Standardized Alarm Signal, specifies that the
smoke alarm's alarm signal
must have a repetitive "three pulse" temporal pattern.
The bandpass filter 11 could be realized with a circuit as simple as a first-
order Butterworth bandpass filter
circuit. Such a circuit would require only a single resistor, capacitor and
inductor. The threshold detector 12
can be realized by selecting an audio transducer with an appropriate
sensitivity rating. The counter 13 could
be realized using a single divide-by-N counter.
There are two important advantages in having this optional audio detector only
enabled after the reminder
period has expired:
= False resets are eliminated since the detector cannot possibly reset the
reminder device until after the
reminder period has expired, and,
0 It will not draw any current until after the reminder period has expired
(extending the life of the battery).
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It is noted that the reminder device can still provide regular reminders if
the optional audio detector is not
included - only the audio reset feature would not be available. It is also
noted that, while Fig. 3 shows these
three stages in a serial configuration for conceptual purposes, any other
combination or embodiment of these
stages could be realized. The important concept is that having one or more of
these three stages greatly
increase the chances that the reminder device will only reset when held close
to a real smoke alarm is being
tested.
Fig. 4 shows three views of one possible embodiment of the reminder device,
i.e. packaged as a battery-
powered 'fridge magnet' reminder with a visual indicator. A bezel 14 is
attached to the front of the device
housing 15, which houses all of the device's components. The bezel has a
colorful 'reminder' graphic and an
opening for the visual indicator 2 (a flashing light emitting diode in this
embodiment). Internal to the device
housing, all components are mounted on a single circuit board.
The manual reset button 6 is accessible through a small hole in the side of
the housing 15. This button is
recessed to avoid unintended resets when handling the device. A pencil or
other similar pointed implement
can be used to press the reset button.
One or more magnets 16 are mounted on the rear of the device to hold it firmly
to the fridge door. The static
magnetic field from these small magnets does not affect the correct operation
of the circuitry.
An opening 17 in the rear of the housing 15 provides a sound path for the
internal audio transducer S. When
the device is removed from its mounting location, it is held with its rear
facing the smoke alarm being tested.
This provides a clear sound path from the smoke alarm to the audio transducer,
as well as positioning the
indicator towards the user (so he can see when the device has reset).
An access port 18 is provided for access to the intemal battery.
