Voice transmitting apparatus for a breathing mask

An apparatus for transmitting the wearer's voice is mounted inside a breathing mask and includes a microphone and a protective sheath substantially encasing the microphone. The protective sheath includes a thin, pliable wall which is kept in contact with the sensing diaphragm of the microphone so that, when the wearer speaks and sets the sheath wall into vibration, the vibration is directly communicated to the microphone diaphragm. In one illustrative embodiment, the sheath is formed as an integral, continuous pocket in the mask body which extends inside the mask and has an opening out of the mask.

BACKGROUND OF THE INVENTION 
The invention relates generally to breathing masks adapted to be worn on 
the face of a human being, and in particular to an apparatus for use with 
a breathing mask to transmit the wearer's voice outside the mask. 
Breathing masks are well known in the prior art. Such masks are used, for 
example, by military jet pilots to aid them in breathing at high 
altitudes. A typical mask includes a generally cup-shaped main body which 
is made of a pliable, air impermeable material, such as rubber; and the 
main body is coupled to a source of an oxygen-rich breathing mixture by 
means of a hose, or the like. In use, the mask is worn over the nose and 
mouth and forms an air-tight seal with the wearer's face. In most cases, 
the mask is also provided with a strap which passes around the wearer's 
head and holds the mask in place so that the wearer can have his hands 
free while breathing through the mask. 
In order to permit the wearer to transmit his voice outside the mask, prior 
art masks have included built-in microphones. Unfortunately, the 
introduction of a microphone into the interior environment of the mask 
introduces a number of problems which, until the present invention, have 
not been adequately solved. First of all, it is very dangerous to include 
an electrical device such as a microphone in an oxygen-rich environment 
because of the ever present danger that an electrical spark may ignite the 
oxygen within the mask. In addition, the oxygen-rich environment and 
moisture introduced from the wearer's breath may very rapidly corrode the 
metal parts of the microphone. Furthermore, the microphone, which senses 
sounds inside the mask and communicates with a point outside the mask, has 
always either been mounted so that it penetrates the body of the mask or 
has been mounted inside the mask and has included an electrical connector 
that penetrated the body of the mask. In either case, openings must be 
provided in the body of the mask, and, even if these openings can be 
sealed adequately when the mask is new, they often leak as the mask ages 
or wears with use. 
SUMMARY OF THE INVENTION 
Broadly, it is an object of this invention to provide a breathing mask 
which eliminates one or more of the aforementioned problems in existing 
breathing masks. Specifically, it is within the contemplation of the 
present invention to provide a breathing mask including a built-in 
microphone in which the microphone is isolated from the dangerous and 
corrosive atmosphere within the mask. 
It is another object of this invention to provide a breathing mask with a 
built-in microphone which is isolated from the dangerous and corrosive 
atmosphere within the mask in such a manner that the effectiveness of the 
microphone is not impaired. 
It is yet another object of this invention to provide a voice sensing 
apparatus in a breathing mask, which apparatus is coupled to a point 
outside the mask without penetrating the body of the mask. 
It is also an object of this invention to provide a voice sensing apparatus 
in a breathing mask, which apparatus is reliable and convenient in use, 
yet simple and inexpensive in construction. 
Still other objects and advantages of the invention will in part be obvious 
and will in part be apparent from the specification. 
In accordance with one aspect of the invention, a microphone inside a 
breathing mask is encased in a protective sheath. The sheath includes a 
thin pliable wall which is maintained in contact with the voice sensing 
diaphragm of the microphone. When the wearer speaks the sheath wall is set 
into vibration, the microphone diaphragm likewise vibrates because it is 
in contact with the sheath wall, and the wearer's voice is transmitted (in 
the form of an electrical signal) without material impairment in 
microphone effectiveness. 
In one illustrative embodiment of the invention, a protective sheath, 
constructed as described, is integrally formed as a continuous pocket in 
the body of the mask such that the pocket extends into the interior of the 
mask and has an opening extending out of the mask body. The microphone is 
mounted inside the pocket with its diaphragm-bearing front portion 
directed toward the interior of the mask body and contacting the thin, 
pliable wall which is in the pocket. The microphone's rear portion, to 
which there are connected electric wires, extends outside the mask through 
the pocket opening. As a result of this construction and arrangement, the 
microphone can communicate with the interior of the mask through the thin, 
pliable wall and can be coupled to a point outside the mask without 
requiring holes in the mask body. 
The invention accordingly comprises the features of construction, 
combination of elements, and arrangement of parts which will be 
exemplified in the construction hereinafter set forth, and the scope of 
the invention will be indicated in the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the details of the drawing and, in particular, to FIGS. 1 
and 2, there is shown a first breathing mask, indicated generally by the 
numeral 10, which incorporates objects and features of the present 
invention. Mask 10 is applied to the face of the user 12 to form an 
air-tight seal therewith, and is held in position by means of a strap (not 
shown) which passes around the head of the user. The mask 10 is coupled to 
a source of a breathing mixture (not shown) by means of a conventional 
hose 14, which is secured to the mask by conventional means (not shown). 
As best shown in FIG. 2, the mask 10 includes a main body 16 which is 
preferably made of rubber. In order to form an air-tight seal with the 
wearer's face regardless of the size and shape of his features, the 
face-receiving opening 18 of the mask is formed by looping the mask 
inwardly on itself to form a broad surface 20 for contacting the wearer's 
face. The mask body 16 includes an apparatus 21 for transmitting the 
wearer's voice, outside the mask. Apparatus 21 broadly comprises a sheath 
22, discussed more fully hereinafter, which is integrally formed in the 
mask body 16 and a microphone 24 encased in sheath 22. 
A relatively rigid mask shield 42, preferably made of plastic, is mounted 
over mask body 16 to lend support thereto. The shield 42 has a pair of 
apertures 44, 44 therein, and generally mushroom shaped buttons 46, 46 
extends outwardly from mask body 16, and are pressed through apertures 44, 
44 to secure shield 42 to mask body 16. At its lower end, shield 42 
includes an integrally formed clip 48 which retains a conventional jack 
50, and a short length of cable 52 is connected between microphone 24 and 
jack 50 to provide means for making a breakable electrical connection from 
a remote point to microphone 24. This connection to microphone 24 is made 
by means of a cable 54 having a conventional plug 56 at its end. A 
conventional cable clamp 58 is mounted on hose 14 to support cable 54. 
Microphone 24 has a housing 60, preferably made of plastic, which has a 
generally cylindrical side wall 61 and a top wall 62. Cylindrical flange 
64, which is concentric with side wall 61, extends above top wall 62 and 
receives a cap 66 which has a central aperture for receiving a bolt 68. As 
will be more fully explained below, flange 64, cap 66 and top wall 62 
cooperate to form a chamber 67 for receiving cable 52. The bolt 68 also 
extends through a central aperture in top wall 62, and a nut 70 which is 
received in a concentric recess 72 in the undersurface of top wall 62, is 
secured at the lower end of bolt 68. In this manner, cap 66 is securely 
fastened to housing 60. Cable 52, which has a pair of wires 53, 53 that 
provide an electrical connection to microphone 24, enters the microphone 
via cut outs in flange 64 and cap 66, passes between cap 66 and the top 
wall 62, is wrapped around a post defined by bolt 68, and passes through a 
hole in top wall 62 (see FIG. 4) into the interior of microphone 24. When 
nut 70 is tightened on bolt 68, cable 52 is clamped between cap 68 and top 
wall 62, so that strain relief is provided against cable 52 being pulled 
out of its connection with the interior of microphone 24. 
A toroidal permanent magnet 74 is mounted inside housing 60 concentrically 
with side wall 61. A metallic disc 76 which is secured in a recessed seat 
78 in the lower edge of side wall 61, a metallic sleeve 80 which is 
received in a recessed seat 82 formed on top of disc 78, and a metallic 
disc 84 which is mounted in a flanged seat 85 on the undersurface of top 
wall 62 cooperate to retain magnet 74 in housing 60. Disc 76 and cylinder 
80 are constructed to form a toroidal air gap 86 about the lower porton of 
the periphery of magnet 74. In the illustrative embodiment discs 76 and 84 
and cylinder 80 are made of a magnetic material, so that the flux from 
magnet 74 is concentrated in the gap 86. A diaphragm 88 is mounted across 
the open bottom of housing 60 and has secured thereto a toroidal winding 
90 which is connected to wires 53, 53 and which extends upward into gap 
86. 
In operation, diaphragm 88 is subjected to vibration, for example, by a 
noise such as the wearer's voice, whereby the winding 90 secured thereto 
is caused to fluctuate within the concentrated magnetic filed in gap 86. 
As a result, an electric current representing the noise sound which 
actuated the diaphragm is induced in winding 90 and is transmitted over 
cable 52. 
As best seen in FIGS. 2 and 3, sheath 22 is integrally formed as a pocket 
in mask body 16 and extends into the interior thereof. Sheath 22 froms a 
continuous pocket in body 16 in the sense that it has no openings into the 
interior thereof which extend into the outside environment. Sheath 22 does 
have an opening 92 which extends out of mask body 16 but this opening does 
not extend to the interior of the mask. In the opening 92 there is formed 
a thick flange 94 defining an aperture 96 of smaller diameter than the 
outside diameter of flange 64. The lower portion of sheath 22 includes a 
thin, pliable wall 98 which contacts diaphragm 88 when microphone 24 is 
inserted inside sheath 22. To achieve this insertion, the aperture 96 is 
forced open by spreading the flange 94, and microphone 24 is inserted. 
When flange 94 is released it bears against flange 64 as shown in FIG. 3, 
because the outside diameter of flange 64 is larger than the diameter of 
aperture 96. As a result, of its resilience, flange 94 firmly presses 
against flange 64 and forms an effective seal therebetween, and, in 
addition, applies a forch which presses microphone 24 downwards, so that 
diaphragm 88 is firmly held against wall 98. In operation, the wearer's 
voice excites wall 98 and causes it to vibrate. As a result of the contact 
between wall 98 and diaphragm 88, the latter is forced to vibrate with the 
former and a signal is transmitted via cables 52 and 54 to a remote point, 
as previously explained. 
Referring now to FIG. 5, there is illustrated in an alternate embodiment of 
a breathing mask 110 incorporating objects and features of the present 
invention, which mask is shown in its normal operating position on the 
face of the user. For consistency, components of the mask 110 which are 
identical to those in mask 10 will be represented by the same reference 
numeral. Like mask 10, mask 110 is connected to a source of a breathing 
mixture (not shown) through a conventional hose 14, which hose is secured 
to the mask by means of a conventional hose-receiving fitting 26 and a 
hose clamp 40. 
Referring now to FIG. 6, it will be observed that the mask includes a main 
body 116 which includes a relatively rigid front portion 118, preferably 
made of plastic, and a pliable rear portion 120, preferably made of 
rubber. Portions 118 and 120 of mask 116 are securely bonded at 122 to 
form a seam that will not leak or open under normal use. Rear portion 120 
has an opening 124 for receiving the wearer's nose and mouth, and like 
body 16 of mask 10 is looped inwardly on itself to form a broad surface 
126 to seal the mask against the face of the wearer despite the actual 
size and shape of his features. 
Within the mask 110 there is included an apparatus 135 for transmitting the 
voice of the wearer which broadly comprises a microphone 136 of 
conventional design and a sheath 138, preferably made of rubber, which 
substantially encases the microphone 136. Like microphone 24 of the first 
embodiment, microphone 136 includes a voice sensing diaphragm (not shown), 
and sheath 138 has a thin, pliable wall 140 which contacts the microphone 
diaphragm. As a result of providing this contact between wall 140 and 
microphone diaphragm, there is no noticable reduction in the performance 
and effectiveness of microphone 136 when the protective sheath 138 is 
placed thereover. 
Microphone 136 includes a connector member 142 which has a face or wall 143 
adapted to be mounted to the inside of wall portion 118. A pair of 
electrical plugs 144, 144 (see FIG. 7) are connected to the interior of 
microphone 136 and protrude from mounting wall 143. The connector 142 is 
positioned inside the mask 116 immediately above hose connector 26 and in 
registration with aperture 145 in wall portion 118. Mounting wall 143 
engages the interior of mask portion 118 at the periphery of aperture 145 
and is secured in this position in a manner to be described more fully 
hereinafter. With connector 142 in its secured position, the plugs 144 
extend through aperture 145 in mask portion 118. An electrical connector 
146, which has a mounting face or wall 147 for engaging the exterior of 
mask portion 118 about the periphery of aperture 145 and includes 
receptacles for the plugs 144, is secured by means of bolts 148, 148 to 
connector 142. For this purpose, bolts 148, 148 pass through connector 146 
and are anchored in connector 142. When the bolts 148 are tightened, the 
part of mask portion 118 defining the periphery of aperture 145 is 
sandwiched between walls 143 and 147 of the connectors 142 and 146, 
respectively; so that both connectors seal against mask portion 118 and 
are securely held in place. Coupled to the receptacles for plugs 144, 144, 
the connector 146 includes a conventional plug 150 which protrudes 
therefrom and provides electrical access to microphone 136. Microphone 136 
is electrically coupled to a remote point by means of a cable 54 which 
terminates in a conventional jack 56. To establish the connection the jack 
56 is mated with the plug 150 on connector 146. 
Although specific embodiments of the invention have been described for 
illustrative purposes, it will be appreciated by one skilled in the art 
that many additions, substitutions and modifications are possible without 
departing from the scope and spirit of the invention as disclosed in the 
accompanying claims. In particular, it will be understood that the 
invention is not limited to use in breathing masks for pilots, but could 
equally well be employed in other types of masks such as drivers' masks or 
gas masks. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained and, 
since certain changes may be made in the above construction without 
departing from the spirit and scope of the invention, it is intended that 
all matter contained in the above description or shown in the accompanying 
drawings shall be interpreted as illustrative and not in a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein described 
and all statements of the scope of the invention which, as a matter of 
language, might be said to fall therebetween.