Note: Descriptions are shown in the official language in which they were submitted.
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BREATHING MONITOR
Background and SummarY of the Invention
To a parent, the medical condition known as Sudden
Infant Death Syndrome (SIDS) or apnea is a frighteni ng
specter which causes many a sleepless night. As is well
5 known, SIDS is a major cause of death in babies and
strikes unexpectedly and often with no warning symptoms.
The only effective preventative is a surveillance of the
infant. This surveillance has been achieved by parents
essentially " St~n~; ng guard" over their infants through-
lO out the night in one extreme. To a lesser extent, par-
ents have relied on other devices such as walkie talkies
left in an open mike condition so that the parent may be
reassured by the sound of the infant breathing. While
hospitals have developed sophisticated and expensive
l5 devices which monitor infants in cribs, the inventor
herein is not aware of any device which has been devel-
oped and is presently being marketed on a commercial
scale of suitable design and cost for home use. While
there have been many prior art attempts at such a device,
20 none has been successful in solving this need. The de-
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vice in the prior art which perhaps comes closest to
achieving this is shown in U.S. Patent No. 4,696,307.
The device disclosed in the '307 patent is described as
being a self-cont~in~A device which is strapped around
5 the torso of a child, the device having an adhesive lin-
ing area for adhering it directly to the child's skin and
a me~h~nical displacement tr~ncAllce~ which is centrally
located within the device such that as the belly of the
child deflects upon the child's breathing, the mech~nical
10 actuator is actuated. An electronic circuit which moni-
tors the transducer sounds an alarm if it determines that
the child is not breathing. The '307 patent states that
the adhesive portion of the box is essential for obtain-
ing a significant response by the transducer as the
15 baby's belly moves during breathing. This ~A~e-~ive at-
tachment provides a reference position and pressure
against which the -ch~nical actuator works to produce a
signal indicative of the baby's breathing.
Although the inventor herein has not a~e ~ ed to
20 test the device disclosed in the '307 patent, it is be-
lieved that there are significant disadvantages thereto.
For example, proper application of the device to a baby,
with the attPnA~nt adhesive attachment of the box to the
baby's skin, must be quite time-consuming, uncomfortable
25 for the baby, and unreliable in that untrained parents
would generally be applying this device to their own
baby. Furthermore, this device relies on a baby's belly
moving in and out as a baby breathes. However, in some
babies it is possible that the deflection of the belly is
30 not as great as in other babies and there is no way to
adjust the device for this required difference in sensi-
tivity. While the '307 patent does suggest that ultra-
sound or hydraulic fluid could be used in place of the
mech~nical transducer, such would not eliminate the re-
35 quirement that the device be adhered to the baby's stom-
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ach or that there be some pressure exerted on the baby's
stomach which could very well be uncomfortable.
Perhaps most im~oL~a1,tly, it is not clear to the
inventor that the device in the '307 patent would reli-
~ 5 ably function. It is this concern which has probably
interfered with the commercialization of this prior art
device as there is certainly a long-felt need for such a
device in order to avoid deaths of infants through SIDS.
In order to solve these and other problems in the
lO prior art, the inventor herein has s~ ree~e~ in designing
and developing a breathing monitor which is self-
cont~in~, battery operated, includes an electronic cir-
cuit with an LED which flashes in response to each
breath, an audio alarm in the event there are no breaths
15 detected within a given preselected time period, and a
fluid filled bladder coupler which interfaces between the
entirety of the device and the baby in order to provide
maximum sensitivity with minimal discomfort to the baby
and, most importantly, reliable operation. A spring
20 lo~ed tension adjuster type ~-o~nector secures an end of
an elastic strap to the device enclosure such that it may
be snugly fastened about the baby and adjusted to within
a proper operating range as indicated by a visual indica-
tor to the parent, thereby affirming to the parent that
25 it has been properly installed. This r,onne~tor also pro-
vides for a limited amount of expansion and contraction,
permitted through withdrawal and retraction of the con-
nector from the device enclosure, to accommodate a baby's
normal breathing. This further increases the comfort of
30 the device as it is applied to a baby in that the '307
device does not provide for any such expansion or con-
traction. However, more importantly, this ro~nector per-
mits an ~n~xpprienced parent to reliably attach the de-
vice to his or her baby and be assured that the device is
35 properly secured and will function properly. This is a
major conc~rn as parents must be assured that the device
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is properly instA~ in order that they may be relieved
and not suffer the anxieties previously felt when no
device was available.
As ment~oT~etl above, a fluid filled bl~A~r coupler
5 interfaces between the device enclosure and the baby.
Unlike the device in the '307 patent, there is no direct
contact between the device enclosure and, certainly, no
~hec~ve contact required between the device enclosure
and the baby's skin. As such, the present invention may
10 be secured about a baby's night clothes or under garments
and yet operate reliably as it responds to a change in
tension in the elastic strap which secures the device
enclosure to the baby. Furthermore, the invention may be
applied to either the baby's back or belly and is not
15 strictly limited to contact with the baby's belly as in
the device in the '307 patent. This particular feature
can be quite important because there is presently contro-
versy with regard to the proper sleep position for babies
in order to minimize the onset of SIDS. Some medical
20 practitioners believe that babies should sleep on their
backs which would ~c~ date application of the inven-
tion to a baby's belly while other practitioners believe
that babies should sleep on their bellies which would
require application of the invention to the baby's back.
25 In either orientation, the present invention will work
for the purposes int~n~e~.
The inventor has also solved the problem of indi-
cating that the battery is losing its charge and needs to
be replaced so that a parent can be assured that battery
30 failure will not attribute to the failure to detect a
baby's cessation of breathing in the middle of the night.
By cleverly designing the electronic circuit, minimal
power drain is achieved such that a single nine volt
battery will provide continuous operation for many
35 months. S~r-on~ly~ the electronic circuit is designed so
that an LED flashes as the baby breathes. If the battery
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is charged sufficiently such that the LED flashes as the
baby is r' ~c~ in its crib for sleep, the battery will
have sufficient charge to last at least through that
sleep period. Should the LED not flash as the monitor is
5 strapped onto the child, then a parent will know that the
battery has discharged dangerously low and needs to be
replaced. Although this design provides fail-safe opera-
tion, it is anticipated that many parents will routinely
replace the ba~ely much more frequently due to the rela-
10 tively low cost of the ba~L~ly and their unf~ ng con-
cern for the safety of their child. Nonetheless, in many
cases, it is anticipated that a single nine volt battery
will last sufficiently long to see the baby through the
riskiest first year of life.
While the principal advantages and features of the
present invention have been described above, a more com-
plete and thorough underst~n~ ng of the invention may be
att~ne~ by referring to the drawings and description of
the preferred embodiment which follow.
20 Brief Description of the Drawinqs
Figure 1 is a perspective view of the breathing
monitor and strap of the present invention;
Figure 2 is a front view of the device enclosure;
Figure 3 is a side view of the device enclosure;
Figure 4 is a cross-sectional view taken along the
plane of line 4-4 in Figure 1 and detailing the interior
mounting of the electronic circuit including LED, audio
alarm, and battery;
Figure 5 is a perspective view of the ~-o~n~-ting
30 rod which co~nects the strap end with the enclosure;
e Figure 6 is a partial cross-sectional view taken
along the plane of line 6-6 detailing the application of
the device around a baby's torso;
Figure 7 is a top view partially broken away to
35 detail the piezoelectric detector mounted within the
enclosure; and
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Figure 8 is a schematic diagram of the electronic
circuit ~cloced within the device.
Detailed Description of the Preferred Embodiment
As shown in Figure 1, the breathing monitor 20 of
5 the present invention includes a device enclosure 22 with
a fluid filled bl~lA~ r coupler 24 secured to and substan-
tially covering one side thereof and an elastic strap 26
which is affixed at one end of ~nCl ocure 22 with an ad-
justable ~o~n~tor 28 at the other end thereof for ad-
10 justably securing it to the opposite side of the enclo-
sure 22. The ad;ustable ~o~ne-ctor 28 includes the push
rod 30 as best shown in Figure 5 which has a post 32 to
which the buckle attachment 34 on strap 26 is secured, a
shoulder 36 which compresses spring 38 (see Fig. 6)
15 against an interior wall of enclosure 22 as the strap 26
is tightened about a baby's torso. A central color coded
area 40 on push rod 30 is viewable through a window 42 of
enclosure 22 (see Figs. 1 and 6) which indicates to a
parent that the strap 26 has been ~ol~ectly secured about
20 the baby's torso such that spring 38 is ~_- , essed to a
correct operating range for proper operation of the brea-
thing monitor 20. Color coded area 40 is surrounded by a
pair of s~.con~ry color coded areas 44, 46 which indi-
cate, if viewable through window 42, that the strap 26 is
25 either too loose or too tight and should be readjusted.
This tension adjustment ensures proper installation and
use by a parent of the breathing monitor 20. Further-
more, this adjustable ~o~n~ntor 28 provides for a limited
amount of expansion and contraction of the strap 26 about
30 the baby's torso as the baby breathes in order to ensure
the comfort of the baby.
As shown in Figures 2, 4, 6 and 7, the interior of
enclosure 22 also provides an opening 48 through which an
LED 50 is viewable to ind~cate, as it flashes, that the
35 baby is breathing and that the battery is charged. The
electronic circuit (see Fig. 8) is mounted on a PC board
-
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52, including LED 50, and is supported within the enclo-
sure 22, as is well known in the art. An audio alerter
54 is oriented ad~acent still another op~ni ng 56 in en-
closure 22 in order to announce an alarm in the event
5 that the baby's breathing is not detected. An on/off
switch 58 is mounted on PC board 52 and extends through
an op~ni ng in enclosure 22 for turning the breathing
monitor 20 on or off, as desired. A force concentrator
60 impinging on a piezoelectric element 61, to achieve
lO maximum h~n~i ng force on the piezoelectric element 61,
comprises a del,e-; l,OL and is mounted to the back of enclo-
sure 22 and is in direct contact with the fluid filled
b~ ~ coupler 24 which rests against the baby's torso.
It is noted that the fluid filled bladder coupler 24
15 extends along essentially the entirety of the backside of
the enclosure 22 and is in direct contact not only with
force noncentrator 60 but also the enclosure 22 as well.
Thus, fluid filled bladder coupler 24 supports or iso-
lates the entirety of the enclosure 22 from the baby's
20 torso, except for the strap 26 which surrounds the torso.
A nine volt battery 62 or the like is conveniently con-
t~ine~ in enclosure 22 and powers the electronic circuit
as shown in Figure 8.
Turning now to the electronic circuit as shown in
25 Figure 8, a first op amp 64 has its positive input con-
nected to ground and one side of piezoelectric element 61
and its negative input co~nected to the other side of
piezoelectric element 61, with a resistor pair 66, 68
being used to set its gain. As the piezoelectric element
30 61 is actuated by the baby's ex~l ing against force con-
centrator 60, op amp 64 produces a pulse which is applied
through resistor 70 to transistor 72 which shunts capaci-
tor 74. As n~p~citor 74 is part of an RC circuit includ-
ing resistor 76 having a time constant of 35 seco~Ac, the
35 baby's exhaling continuously resets this time delay un-
less a period of greater than 35 secon~s p~sc~-s without a
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breath being taken. To achieve maximum sensitivity, the
piezoelectric element 61 is connected in polarity to
reset the time delay as the baby exhales rather than on
inhale as the inventor has found the act of exhaling to
5 be a more abrupt movement. A pulse from op amp 64 also
passes through ~Ap~r-~tor 78 to turn on transistor 80
which pulses LED 50 to provide a visual indication that
the baby has exhaled. A resistor bridge 79, 81 hT~c~
transistor 80 just below its turn on point to adjust the
lO sensitivity of transistor 80 to the pulse generated by op
amp 64. Also, resistor 83 limits the current through LED
50, as known in the art.
A second op amp 82 has its positive input biased
to a set voltage by a pair of resistors 84, 86. If the
15 voltage across capacitor 74 charges above this set volt-
age, then the output of op amp 82 goes negative which is
applied to the base of transistor 88 by resistor 90 to
thereby turn it on and actuate audio alerter 54 to indi-
cate to a parent that the baby has not taken a breath for
20 the 35 c~onA time constant.
Transistors 92, 94 act as a low battery voltage
indicator circuit. A pair of resistors 96, 98 bias tran-
sistor 92 on until battery voltage drops below a no~n~
eight volts. At that point, transistor 92 turns off
25 which permits transistor 94 to turn on with base current
through resistor lO0. With transistor 94 being turned
on, base current to transistor 80 is shunted therefrom,
thereby turning off transistor 80 and disabling LED 50
from being flashed. Thus, should a parent strap the
30 breathing monitor 20 around a baby's torso and, while
watch;ng the baby breathe, the LED 50 fails to flash, the
parent knows immediately that the battery needs to be
replaced. Alternately, if the LED 50 is fl~sh; ng, the
battery is adequate and the parent may be assured that it
35 is functioning properly.
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The inventor has found that the fluid filled
bladder coupler 24 with force ~o,~ntrator 60 and piezo-
electric element 61 is incredibly sensitive. The fluid
filled bladder coupler 24 may be filled with any sterile
~ 5 fluid, the inventor having used saline in a pLuLo~y~e.
However, it is anticipated that any fluid, gel, or the
like which provides a "soft" coupling might ~ust as well
be used and perform satisfactorily. As previously noted,
fluid filled blAA~er coupler 24 supports the entirety of
lO the enclosure 22 from the baby's torso, and there is no
direct contact between the enclosure 22 and the baby's
torso. This effectively isolates the enclosure 22 and
dramatically increases the sensitivity. This provides
tremendous advantages in not only sensing the breathing
15 motion of the baby, but also in providing comfort to the
baby to minimize interference with the baby's sleep.
This comfort and sensitivity is Pnh~n~ by the adjust-
able tension ~onn~tor between the strap and enclosure
which permits a limited amount of deflection of the elas-
20 tic strap with respect to the enclosure as the babybreathes. These features ~h~nce the operation of the
present invention.
While the description of the preferred embo~iront
of the invention details its use with a baby, the inven-
25 tion also has utility with people of any age and even ananimal such as a dog. In some veterinary procedures, it
is desirable to monitor the breathing of an animal. For
example, as a dog is being operated on and while it is
recovering from any anesthesia it would be desirable to
30 use the invention to ensure that any interruption in
breathing is corrected. Such other uses are intP~e~ to
be covered by the claims appended hereto.
There are various changes and modifications which
may be made to the invention as would be apparent to
35 those skilled in the art. However, these changes or
modifications are included in the te-~r-h; ng of the disclo-
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sure, and it is inten~ that the invention be limited
only by the scope of the claims appended hereto.
