U.S. patent number 3,562,451 [Application Number 04/736,213] was granted by the patent office on 1971-02-09 for microphone and headset for underwater swimmer.
This patent grant is currently assigned to THE United States of America as represented by the Secretary of the Navy. Invention is credited to Ollie G. Kirkpatrick, Walter W. Mullen, Jr..
United States Patent |
3,562,451 |
Mullen, Jr. , et
al. |
February 9, 1971 |
MICROPHONE AND HEADSET FOR UNDERWATER SWIMMER
Abstract
An improved headset and microphone construction for use in
aqueous environts of high ambient pressure and a method of
manufacture thereof.
Inventors: |
Mullen, Jr.; Walter W. (Panama
City, FL), Kirkpatrick; Ollie G. (Panama City, FL) |
Assignee: |
THE United States of America as
represented by the Secretary of the Navy (N/A)
|
Family
ID: |
24958968 |
Appl.
No.: |
04/736,213 |
Filed: |
June 11, 1968 |
Current U.S.
Class: |
381/334; 381/54;
381/378; 381/376; 367/160; 367/162; 367/165; 379/175; 381/190 |
Current CPC
Class: |
H04M
1/05 (20130101) |
Current International
Class: |
H04M
1/05 (20060101); H04M 1/04 (20060101); H04r
017/00 () |
Field of
Search: |
;179/110.1,187 ;340/10,8
;181/.5 ;310/8.5,8.6,9.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Claffy; Kathleen H.
Assistant Examiner: Kundert; Thomas L.
Claims
We claim:
1. An audio transducer for use in aqueous, subsurface environments
comprising:
a molded, flexible, body-fitting means;
a pocket molded into the interior of said flexible, body-fitting
means and communicating with one surface thereof;
a passageway through said flexible body-fitting means connecting
the exterior thereof to said pocket;
a metallic sleeve member in said pocket substantially coextensively
with the outer edge thereof, having an aperture aligned with said
passageway;
electroacoustic transducer means disposed within said pocket, and
within the confines of said metallic sleeve member so as to be
spaced therefrom, said electroacoustic transducer including:
a first platelike, piezoelectric crystal having two major faces and
a piezoelectric axis;
a thin, flexible, metallic electrode, with a first face thereof
being secured to one of the major faces of said first piezoelectric
crystal, said electrode having an area greater than said platelike
piezoelectric crystal so as to extend therebeyond;
a second platelike, piezoelectric crystal having two major faces,
one of which is secured to a second face of said thin, flexible,
metallic electrode opposite to said first face thereof in alignment
with said first platelike piezoelectric crystal, and having a
piezoelectric axis differently oriented than the piezoelectric axis
of said first platelike piezoelectric crystal;
two surface electrodes on the major faces of the first and second
platelike, piezoelectric crystals not joined to the aforesaid thin,
flexible, metallic electrode and coextensive therewith;
an insulated electrical conductor means passing through said
passageway, dimensioned to effect a watertight seal therewith, and
passing through said aperture in said metallic sleeve member and
enclosing therein a first and a second electricity conducting
means;
said first electricity conducting means being effectively attached
to said two surface electrodes to provide electrical circuit
connection therewith;
said second electricity conducting means being effectively attached
to said thin, flexible, metallic electrode to provide electrical
circuit connection therewith;
a layer of silicone rubber material filling at least a portion of
said pocket and encapsulating said piezoelectric element, so as to
position it within the confines of said pocket and sleeve member;
and
retaining means at the said one surface of said molded, flexible,
body-fitting means cooperating therewith to extend across the
pocket communicating therewith and thereby retain said encapsulated
electroacoustic transducer means therewithin.
2. An audio transducer according to claim 1 in which said insulated
electrical conductor is bonded to the walls of said passageway.
3. An audio transducer according to claim 1 in which said molded,
flexible, body-fitting means is shaped to closely fit about the ear
region of the average human head.
4. An audio transducer according to claim 1 in which said molded,
flexible, body-fitting means is shaped to closely fit about the
nose and mouth region of the average human head.
5. An audio transducer according to claim 1 in which said retaining
means comprises a preformed sheet of synthetic rubber material
fitting within a recess in said one surface of said molded,
flexible, body-fitting means and adhesively secured thereto,
extending across said pocket, and adhesively secured to the said
layer of silicone rubber material.
Description
This invention relates to voice communications between personnel
beneath the surface of a body of water and in particular to an
improved construction of the terminal elements, i.e., the headset
and microphone, used in this communication system.
Modern oceanographic technology has given rise to many endeavors in
which teams of personnel are required to work beneath the surface
of the water in close cooperation. These demands have resulted in
the electronic components of the communication systems being
improved many fold from the beginning systems of a short while ago.
Despite the remarkable advances in the electronic portions of the
systems, the development of improved terminal elements has been
less rapid.
In prior art headsets and microphones for use under the water, the
sound transducers are encased in a gas or air filled enclosure at
atmospheric pressure and sealed against the influx of water under
the pressure corresponding to that encountered at the expected
depth of operation. This construction, while satisfactorily
avoiding water-caused shorting, limits effective operation as a
sound transducer by virtue of acoustic properties of the different
transmitting mediums. The original water seal is also troublesome
to maintain under the pressure and temperature changes encountered
in subsurface operations. Too, prior art constructions were often
quite fragile for the arduous conditions encountered while working
below the surface of the water.
It is accordingly an object of this invention to overcome the
aforementioned limitations of the prior art, and to provide
effective terminal elements of an improved construction for use in
an underwater environment and a method for the manufacture
thereof.
A further object of this invention is the provision of an improved
headset for use in underwater applications, and a method of
manufacture thereof.
A further object of this invention is the provision of an improved
microphone construction which is compatible with existing diving
masks and other diving equipment and a method of making said
microphone.
Other objects and many of the attendant advantages will be readily
appreciated as the subject invention becomes better understood by
reference to the following detailed description, when considered in
conjunction with the accompanying drawings wherein:
FIGS. 1 and 2 illustrate the devices of the invention as worn by a
diver;
FIG. 3 shows a block diagram of a communication system using the
terminal devices as taught by the invention;
FIGS. 4 and 5 illustrate a microphone construction according to the
invention which is compatible with diving masks and underwater
breathing apparatus designed for conventional microphone
constructions;
FIGS. 6 and 7 show constructional details of the headset made in
conformity to the teachings of the invention; and
FIG. 8 depicts an alternate construction of a microphone mounting
which is analogous to the constructional techniques employed in
manufacture of the headset.
As shown in FIGS. 1 and 2, a face mask 11, worn by an underwater
swimmer, has a facially conforming breathing mouthpiece 12 carried
therewithin in such a position that it closely fits over the mouth
and nose of the swimmer. Mouthpiece 12 communicates with swimmer
worn gas bottles, not shown, via coupling means 13, external to
mask 11. A microphone 14 is held by suitable mounting within
breathing mouthpiece 12 and in close proximity to the mouth of the
swimmer. An electrical conductor 15, which is preferably coaxial
cable designed for this purpose, joins microphone 14 to connector
16 and thence, via cable 17, to appropriate circuitry 18 (FIG. 3),
to be described, presently, in greater detail.
The swimmer receives audio signals via two receivers 19 which, as
shown in FIGS. 1 and 2, are joined by a headband 21 and
electrically united with connector 16 by a conductor 22. Headband
21, together with suitable unillustrated pockets or other structure
forming a part of mask 11 or a diving suit of the swimmer, locates
receivers 19 in cooperative location relative to the ears of the
swimmer for transmittal of sound thereto. Cable 17, which is joined
to conductors 15 and 22 by connector 16, is sufficiently long to
permit the swimmer to have the desired degree of mobility to
accomplish the particular underwater task which he undertakes and
has conductors for carrying the signals from microphone 14 and to
receivers 19. Cable 17 may be brightly colored, if desired, to
minimize the chances of accidental severing by the swimmer in
performance of his underwater tasks.
The basic circuit for interconnection of two swimmers to permit
voice communication therebetween is diagrammatically illustrated in
FIG. 3. Blocks 23 and 24 represent a first and second swimmer,
respectively, and include microphones 14 and 14a and receivers 19
and 19a, respectively. Cables 17 and 17a, as explained above,
connect each swimmer to circuitry 18. For purposes of clarity,
provision for only two swimmers is shown but it is understood that
more may be, and generally are, accommodated by circuitry 18. It
should also be understood that circuitry 18 may be physically
located either beneath, or above, the surface of the water, as, for
example, in an underwater environment station or aboard a surface
vessel.
Circuitry 18 comprises a mixer-preamplifier 25 which combines the
electrical signals fed by cables 17 and 17a, increases the
electrical magnitude thereof, and feeds the thus increased signals
to a helium speech processor 26. The electrical output of the
helium speech processor 26 is amplified by an amplifier 27 and is
fed, via cables 17 and 17a, to receivers 19 and 19a.
The use of helium gas to replace nitrogen, the principal gas in
normal surface air, is accepted to avoid undesirable effects of
nitrogen on the body when breathed in high pressure environments.
Because of the different density of the helium-oxygen mixture from
that of surface air, the speech of the breather is highly
distorted. The purpose of the helium speech processor is to
electrically synthesize a normal speech signal from the signal
generated by microphone 14 when activated by the voice of a
helium-oxygen breathing swimmer. A variety of such circuits are
known and, since no individual one is required for use with the
microphone and receiver construction of the instant invention, a
detailed description thereof is not considered necessary.
With reference to FIGS. 4 and 5, the constructional details of one
form of the invention may be seen. FIG. 5, it will be observed, is
a sectional view taken along line 5-5 of FIG. 2. In this form of
the invention, a metal sleeve 28 houses a microphone element,
indicated generally at 29.
Microphone element 29 is piezoelectric element which flexes or
bands in response to compressional waves from the speech organs of
the swimmer. A particularly satisfactory construction of this
element joins two face-shear cut piezoelectric plates 36 and 37,
which may be of .024" inch thick lead zirconate, on either side of
a flexible metallic electrode 35. The axis of plates 36 and 37 are
arranged in such a fashion that the dimensions of electrostatic
expansion extend in different directions. This construction causes
the unit to twist rather than bend relative to a single axis and
results in a unit that is many times more sensitive and more linear
with a change of temperature than a single element. Deposited
surface electrodes 31 and 32 on the outer faces of the assembly
permit parallel or series connection of the two piezoelectric
plates into a two terminal devices. For purposes of explanation,
microphone element 29 has surface electrodes 31 and 32 connected to
outer conductor 33 and center conductor 34 of coaxial conductor 15
in a series connection with the centrally disposed flexible
electrode 35 electrically uniting the faces of piezoelectric plates
36 and 37 which are remote from surface electrodes 31 and 32.
Should a parallel connection be desired, surface electrodes 31 and
32 may be joined, a first external connection made thereto, and a
second external connection made to the flexible center electrode
35, as shown in FIG. 5.
The microphone element 29, joined to conductor 15, is placed within
sleeve 28 with cable protruding through aperture 39. Sleeve 28 is
then filled with a potting material 38 to a point covering aperture
39 and cable 15, but not covering microphone element 29, and
allowed to harden. This forms a secure mechanical bond between
cable 15 and sleeve 28. Potting material 38 may be any suitable
electrically-insulating, water-impervious material. That marketed
under the trade name "Scotchcast", by the Minnesota Mining and
Manufacturing Company, has proven acceptable. The remaining portion
of sleeve 28 is then filled with a liquid silicone rubber material
40. The resulting rubber encapsulation is lightweight, waterproof,
acoustically transparent, and thermally insulating.
Sleeve 28 is so dimensioned that the completed microphone 14 is
dimensionally equivalent to the prior art constructions thereby
enabling microphone 14 to fit existing diving equipment without
modification thereof. Such an arrangement is shown in FIG. 5.
Mouthpiece 12 has a microphone receiving pocket 41 which contains
microphone 14. A passageway 42 communicating with pocket 41 and
fits cable 15 with sufficient tightness to render the
cable-mouthpiece joint watertight. Pocket 41 also has lips 43 which
are located about the mouth thereof and extend partially
thereacross to constitute microphone retaining means.
The silicone rubber material 40 is sufficiently pliable to permit
microphone element 29 to flex slightly in response to the sound
waves generated by the voice of the swimmer. Because of the
aforementioned increased sensitivity afforded by the construction
of microphone element 29, the slight flexure permitted by the
rubber material 40 is sufficient to obtain a signal of useable
magnitude.
A similar construction technique to that employed with respect to
microphone 14 is used in the construction of an improved receiver
assembly, as shown in FIGS. 6 and 7. Receiver body 44, which may be
shaped to conform with the head of a user, is made of molded rubber
material and has a molded pocket 45 therein. A passageway 46, best
shown in the sectional FIG. 7, communicates with pocket 45 and the
exterior or receiver body 44 and carries conductor 22 therethrough.
The insulation of conductor 22 may be vulcanized, during the
molding process, to receiver body 44 to effect an improved seal
therebetween. Conductor 22 carries two wires 47 and 48 which are
electrically joined to piezoelectric element 49, lying within
pocket 45. A silicone rubber material 40 fills pocket 45 to the
level of a surrounding recess 51 and encapsulating piezoelectric
element 49. An adhesive-backed, synthetic rubber preform 52, not
unlike that used to close ruptures in pneumatic tubes, is placed
across the pocket 45 in recess 51, thereby inhibiting the
accidental puncture of rubber material 40 to the determent of
piezoelectric element 49. A fastening means 53, shown as an
integrally molded button, on the rear of receiver body 44 fastens
receiver 19 to headband 20. Fastening means 53 may be of any
suitable type in accordance with the desires of the skilled artisan
making the device and that shown should be regarded only as
illustrative.
The synthetic rubber material 40 used in both the microphone 14 and
receiver 19 constructions is of the type that is liquid at room
temperatures and hardens upon exposure to air. This material has
the desirable property of being self leveling and of vulcanizing or
bonding to other rubberlike synthetics at moderate or room
temperatures. This material, when solidified, has the properties of
securing the encapsulated elements against mechanical shock and
rapid thermal variations while offering no undue impedance to
normal, operational vibrations. One such material is known and
marketed under the trade name RTV, manufactured by The General
Electric Company.
The improved construction used in manufacturing the receiver 19 is
applicable to microphone construction, as illustrated at FIG. 8, if
the requirement of compatibility with existing diving apparatus is
not controlling. As shown, the pocket 41 in mouthpiece 12 is
provided with an annular recess 55. Sleeve 28, which may be omitted
in this construction if desired, extends to the inner edge of
recess 53 and is filled to that point with a silicone rubber
material 40 to encapsulate microphone element 29. An
adhesive-backed, synthetic rubber preform 54 fits flush in recess
55 to close pocket 41 and, thereby, protect microphone element
29.
The aforedescribed constructions result in lightweight, compact
terminal devices for use in aqueous, subsurface voice
communications systems. The units are pressure resistant without
incorporating gas-liquid seals, and exhibit excellent response
linearity in a variety of water term temperatures. Further, they
have shown excellent response characteristics to depths of 600
feet. In general, the devices of the invention have exhibited an
unprecedented combination of desirable attributes which belies
their mechanical simplicity and economy of manufacture.
Obviously, other embodiments and modifications of the subject
invention will readily come to the mind of one skilled in the art
having the benefit of the teachings presented in the foregoing
description and the drawings. It is, therefore, to be understood
that this invention is not to be limited thereto and that said
modifications and embodiments are intended to be included within
the scope of the appended claims.
The invention described herein may be manufactured and used by or
for the Government of the United States of America for governmental
purposes without the payment of any royalties thereon or
therefor.
* * * * *