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Патент USA US3100296

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Aug- 6, 1963
F. R. AB‘BOTT
3,100,291
UNDERWATER LOUDSPEAKER
Filed 001;- 25, 1960
F/'g. I
”
l2
TRANSDUCER
EXCITATION
AND
UTILIZATION
MEANS
3/
PUTTING
MA TER/AL.
INVEN 710R.
FRANK R ABBOTT
BY
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@1 A.
' W‘
United States Patent 0 ice
1
3,100,291
UNDERWATER LOUDSPEAKER
Frank R. Abbott, 3953 Wildw'ood, San Diego, Calif.
Filed Oct. 25, 1960, Ser. No. 64,971
13 Claims. (Cl. 340-10)
(Granted under Title 35, US. Code (1952), see. 266)
3,100,291
Patented Aug. 6, 1963
2
cable 12 to an excitation and utilization means 13. Said
transducer is of the reversible type which generates and
broadcasts acoustical energy upon appropriate excitation
by proportional electrical energy and which produces
electrical energy upon excitation by proportional received
acoustical energy.
Electrical cable 12 may be of any
appropriate type which may be submerged in water with
out leaking or shorting and may, for example, be of
coaxial con?guration if expedient or desired. Examples
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 pay 10 of excitation and utilization means 13 are numerous-too
ment of any royalties thereon or therefor.
numerous to de?ne in detai1-—but it should be understood
The present invention pertains to electro'acoustical trans
that any communications equipment may be employed
ducers in general and in particular to an improved loud
that is adapted for generating and receiving appropriate
speaker for projecting relatively high power sonic energy
within an aqueous‘medium with a remarkably ?at re
signals and otherwise cooperatively interacting with trans
15 ducer 111 is herein included.
sponse throughout the ?ve hundred to two thousand cycle
per second frequency band.
FIG. 2 discloses a preferred embodiment of the instant
invention ‘as having an aluminum hemispherical shell 14
The prior art includes, many such loudspeakers, each of
which may be su?iciently satisfactory for‘ its own unique
spatially disposed at substantially the diametrical ‘section
thereof from another aluminum hemispherical shell 15
purpose, but none of which ostensively has the ?delity, 20 in such manner as to form a hollow ball-like structure.
the power per unit weight, or the overall compactness of
Although shown as spherical, metallic shells in FIG. ‘2,
the loudspeaker constituting the instant invention. For
said shells may be of any pertinent predetermined geo
example, the smallest transducers known heretofore to be
metrical con?guration and may be made of ‘?berglass,
available with comparable power, ?delity, and range were,
plastic, or any other suitable material having the proper
generally, at least a foot in diameter, a foot in height, 25 strength characteristics adapted for effecting mechanical
and weighed one hundred pounds or more. Of course,
impedance transformation between same and ambient sea
water.
smaller transducers have been made. However, since
they usually incorporate ?exing ceramic discs, the ?delity
Shells 14 and 15 are held together to form a unitary
of frequency response leaves ‘a great deal to be desired
overall structure but in such manner as to allow relative
and, consequently, they are ordinarily limited to narrow 30 gmovement therebetween along axis X—X by a resilient,
band or perhaps resonant frequency type operations.
?exible, rubber fabric tape ring 16 attached thereto by a
cement 17 or other pertinent connecting means.
The present invention overcomes many‘of the afore
mentioned disadvantages of the prior art devices.
It is, therefore, an object of this invention to provide
Inserted within the hollow portions of shells 14 and
15 is an electrostrictive energy converter 18 which extends
an improved underwater loudspeaker.
35 between the inner surfaces thereof along aforementioned
Another object of this invention is to provide an under
axis X—X. The ends of said energy converter are at~
water speaker having a substantially ?at response through
tached to the inner surfaces of each of said shells, re
out the voice frequency band of ?ve hundred to two
spectively, by means of cements 19 and 20 or other con
necting means as desired.
thousand cycles per second.
Energy converter 18 includes a plurality of piezoelectric
A further object of this invention is to provide a 40
high~power electroacoustic'al transducer that may be used
discs 21 of ferroelectric, polarized barium titanate ceramic,
for communication between submarine divers within one
lead zirconate, or other ferroelectric or telectrostrictive
hundred yards range of each other.
ceramic, or the like. Although in this instance, the afore
said piezoelectric discs are conventionally polarized dur
A still further ‘object of this invention is to provide
an underwater loudspeaker that is comp-‘act in size and
ing the manufacturing process, it should be understood
light in weight for the power and ?delity thereof.
that externally applied polarizing potentials may be ap
Another object of this invention is to provide ‘a rever
plied thereto by the utilization means if so desired, or in
event the phenomenon of double ‘frequency characteristics
sible, broadband, waterproof, electroacoustical transducer
that will broadcast and receive pressure energy through
would not adversely affect overall operation, ‘no polariza
sea water while being submerged therein.
tion of the piezoelectric elements need be included. Abut
Another object of this invention is to provide a light
ting each ‘face ‘of each of said discs is a silver electrode
weight means of voice communication that may be easily
22 which, for example, may have been attached ‘thereto by
carried by submerged sea divers.
being painted thereon in the presence of a removable car
Still another object of this invention is to provide an
rier vehicle and ?red until the vehicle disappears, thus
underwater loudspeaker that is easily and economically 55 leaving the silver securely adhering to the surface thereof.
manufactured and maintained.
Said discs are then stacked along operational axis X——X
Other objects and many of the attendant advantages of
in such manner that adjacent silver electrodes electrically
this invention will be readily appreciated as the same be
contact each other. In the herein disclosed preferred
comes better understood by reference to the following
embodiment of the subject invention, insulated electrical
detailed description when considered in conjunction with
leads 23 and 24 are respectively connected. ‘to the afore—
the accompanying drawing in which like reference nu
said electrodes so that said piezoelectric discs 21 are elec
merals designate like parts throughout the ?gures thereof
and wherein:
trically ‘connected in parallel. However, it should be
understood that it is within the teaching, scope, spirit, and
purview of this invention to electrically connect piezoelec
FIG. 1 is a block diagram illustrating the cooperation
of the transducer constituting this invention with ‘an 65 tric discs 21 in ‘series if operational circumstances so war
exemplary excitation and utilization means therefor.
rant, and that the subject discs ‘and electrodes may be so
FIG. 2 is an elevational view partially shown in cross
insulated and so disposed to achieve such effect. Also, if
section and partially depicted p-ictorially of the under
so desired, said piezoelectric disc assemblies may be ?xedly
water loudspeaker constituting this invention.
connected to each other as appropriate to provide the pre
Referring now to the drawing and FIG. 1 in particular, 70 ferred structural con?guration by means. of an adhesive
there is shown a transducer 11 of the type constituting
inserted therebetween.
the subject invention connected by means of an ‘electrical
In order to alleviate the possibility of shorting and in
3,100,291
4
3
the piezoelectric converter ‘assembly, it is encapsulated
size of said hemispheres in relation to the wavelengths of
the acoustical energy projected thereby, the subject loud
within an epoxy resin chamber which may, for instance,
speaker may have omnidirectional, substantially bidirec
take the (form of a plastic tube 25 having sealed plastic
plugs 26 and 27 at the ends thereof. Moreover, if desired,
any suitable potting material may be used to ?ll any of
the volume of tube 25 not occupied by the aforesaid piezo
tional, or other radiation patterns.
capacita'tion due to the presence of moisture or water on
electric disc and electrical lea-d assemblies. Although optional, in many instances, use ‘of such potting material
Projection of acoustical energy is eifected by supplying
electrical intelligence signals to the toroidal transformer
‘
which increases the voltage thereof and feeds them to
each ‘of the parallel connectedl electrodes and, thus,
to the piezoelectric discs.
Obviously, the toroidal trans
would ostensively improve the strength ‘and insulation 10 former becomes super?uous and may be deleted from the
transducer in event the intelligence signals supplied there
characteristics of the entire electrostrictive energy con
to are already ‘of suflicient voltage to be useful. However,
verter. Furthermore, electrical leads 23 and 24 are
even the large capacitance afforded by parallel connection
brought out of said plastic tube through a waterproof elec
of the piezoelectric discs is ordinarily insu?icient for semi
trical coupling 28 a?ixe-d to the external surface thereof
by means of cement 29 or any other pertinent adhesive 15 conductor or transistor ampli?er drive. Incorporation
of the disclosed toroidal transformer facilitates the use of
or connecting means.
As previously mentioned, the entire piezoelectric con
such ampli?er drives for actuating the transducer. When
polarized, either externally or inherently, to provide a
verter unit is mounted within the ball-like structure formed
?xed electrostrictive bias, the piezoelectric discs expand
by shells 14 land .15 and is attached-thereto at each end
respectively by cement 1'9 and 20 so that movement of the 20 and contract in accordance with the intelligence char
acteristics of the applied alternating excitation current.
ends thereof will likewise move said shells and vise versa.
Because said discs are stacked along a common opera
Of course, any appropriate connecting means may be em
tional axis, the relative movement between ends of con
ployed between these elements, but it has been found to
verter unit becomes the sum of the expansions and con
be economical to manufacture and maintain the subject
transducer when cement is used.
25 tractions of all of the discs combined. .Due to the fact
that the Young’s Modulus of Elasticity of epoxy and plas
Mounted on the outside of the tubular portion of elec
tic resins are less than that of barium titanate, tube 25
trostrictive energy converter 18 is a toroidal transformer
offers only a negligible restraint on the expansion and
30 having approximately ?fty or one hundred to one
contraction of the converter unit, and, accordingly may
turns ratio having a low impedance, tapped, primary wind
ing 31 adapted for matching four, eight, sixteen, or ?fty 30 be disregarded for all practical purposes.
ohm inputs and a high impedance secondary winding 32
Relative movement between the hemispherical shells is
adapted for connection to electrical coupling 28 through
permitted as a result of the cut at the diametrical plane
leads 33. Said windings are electrically insulated from
therebetween and the inter-connection thereof by the resi
each other by insulation 34 and are toroidally wound
lient molded tape ring. Waterproofing of the internal
about a cylindrical laminated silicon iron magnetic core 35 ‘volume of said shells is also conveniently effected by use
35. For support purposes, a sponge rubber mounting
means 40 is inserted between the inside diameter of the
toroidal transformer and the outside diameter of the
of said ring and the adhesive cement used therewith.
Although the above operational expansion has been
primarily directed at using the invention as a projector,
it should be obvious that the, reverse process would cause
energy converter. Although, for many practical pur
poses, a snug ?t has been found su?icient to hold said 40 it to function as a hydrcphone, as well.
transformer and converter in their predetermined relative
In addition, although many of the structural elements
positions during normal operations, a cement 36 may be
of the preferred embodiment have been exaggerated in
used to insure against adverse slippage.
size in order to facilitate disclosure thereof in the draw
Electrical leads 37 connect the primary winding of the
toroidal transformer to a waterproof electrical coupling
, 38 which, in turn, is connected through cable 12 to excita
tion and utilization means 13.
A mounting bracket 39 adapted for connection to a
support means extending from a carrier vessel is attached
to any preferred location on the outer surface of either
.shell 14 or 15. Or, if so desired, said mounting bracket
,may be replaced by a handle which would facilitate the
subject transducer’s being held by the hand of a sub
merged diver.
ing, it should be understood that the proper design choices
regarding size is incorporated as part of the teaching
herein. Thus, for example, the thickness of the silver
electrodes, the thickness of the piezoelectric discs, and
the thickness of the cement therebetween, if any, etc,
should be such as to provide optimum operation during
any given operational circumstances.
Obviously, many modifications and variations of the
present invention are possible in the light of the above
teachings. It is, therefore, to be understood, that within
the scope of the appended claims, the invention may be
Brie?y, the operation of the present invention is as 55 practiced otherwise than as speci?cally described.
follows:
What is claimed is:
While being hand carried by :a submarine diver or sup
»1. An electroacoustical transducer adapted for pro
ported by acarrier vessel, the subject loudspeaker is
jection and reception of sonic energy while being sub
completely submerged in water, where it projects or re
merged within an aqueous medium comprising in com
ceives pressure wave energy in the sonic or acoustical 60 bination, a ?rst hemispherical sonic energy projecting
range of ‘frequencies. Because it is especially e?icient in
the ?ve hundred to two thousand cycle per second fre
quency band, it is particularly useful in human voice oom
means, a second hemispherical sonic energy projecting
means spatially disposed from said ?rst hemispherical
sonic energy projecting means, a piezoelectric energy con
verter means respectively connected to each of said hem
When broadcasting, it, of course, must be excited by an 65 ispherical sonic energy projecting means at the ends there
.munication under water.
‘
appropriate transmitter, and when receiving, it must be
of, resilient means interconnecting said hemispherical
coupled to an appropriate receiving set. In either case,
projecting means for providing a waterproof encasement
the transmitter or receiver may be disposed in close
for said piezoelectric converter means while allowing rela
proximity with the loudspeaker or it may be located at
tive movement therebetween, a toroidal transformer
.some place remote therefrom, depending on the length of 70 mounted on said piezoelectric converter means and elec
the interconnecting cable therebetween.
trically coupled for supplying power thereto, and means
Broadcast of acoustical energy occurs as a result of the
connected to said toroidal transformer for conducting elec
compression and decompression of the ambient water in
contact with the exterior surface of the relatively moving
trical energy thereto from a supply source located exter
nally of said energy projecting surfaces and the resilient
hemispheres. Depending on the design choice of physical 75 means interconnecting same.
3,100,291
2. The device of claim 1 wherein said resilient means
interconnecting said hemispherical projecting means for
providing a waterproof encasement for said piezoelectric
6
10. The means of claim 7 wherein said pair of hollow
hemispherical shells each of which is spatially disposed
[from the other along an axis of geometrical revolution
consists of a plastic material.
converter means while allowing movement therebetween
comprises a rubber fabric tape and cement inserted there
11. In an underwater transducer, an electrostrictive
between.
energy converter comprising in combination, an elongated
3. The device of claim 1 wherein said piezoelectric
epoxy resin tube, a plurality of polarized barium titanate
energy converter means respectively connected to each of
discs disposed along the longitudinal axis of said tube, an
said hemispherical sonic energy projecting means at the
electrode attached to each face of each of said plurality
end thereof includes a stack of parallel connected ferro 10 of polarized barium titanate discs, each of said discs abut
electric discs encapsulated within a plastic tube.
ting others in such manner as to provide electrical contact
4. The device ‘of claim 1 wherein said piezoelectric
between the adjacent electrodes thereof, means con
energy converter means respectively connected to each of
uected to ‘said electrodes for electrically connecting said
said hemispherical sonic energy projecting means at the
discs in parallel, a pair of plugs one of which is disposed
end thereof includes a stack of parallel connected barium 15 in one end of said tube and the other of which is disposed
titanate discs encapsulated within a plastic tube.
in the other end of said tube and both of which simul
5. The device of claim 1 wherein said piezoelectric
taneously support and seal said discs within said tube,
energy converter means respectively connected to each
and an electrical coupling mounted on said tube adapted
of said hemispherical sonic energy projecting means at
for providing a waterproof connection between said plu
the ends thereof includes a stack of parallel connected 20 rality of polarized barium titanate discs and a means of
lead zirconate discs encapsulated within a plastic tube.
electrical excitation for same.
6. The device of claim 1 wherein said means connected
#12. The device of claim 11 wherein said tube is ?lled
to said toroidal transformer for conducting electrical
With a potting material in the space unoccupied by said
energy thereto from a supply source located externally of
discs, electrodes, and connecting means.
said hemispherical energy projecting means and the resi 25
13. An underwater loudspeaker comprising in. com
lient means interconnecting same includes a watertight
electrical coupling, electrical leads connected between
said toroidal transformer and said coupling, and an
electrical cable connected to said coupling and adapted
bination, a pair of spatially disposed hemispherically
shaped shell means adapted for projecting acoustical
energy within an aqueous medium, a resilient ring means
cemented to each of said pair ‘of spatially disposed
to be connected to an external excitation and utilization 30 hemispherically shaped shell means for enabling relative
movement to occur therebetween while providing a water
means.
7. Means for broadcasting and receiving pressure
energy while being submerged within water comprising
proof seal thereat, a plurality of polarized piezoelectric
discs having electrodes attached to the faces thereof, said
discs being disposed along a longitudinal axis of revolu
in combination, a pair of hollow hemispherical shells
each ‘of which is. spatially disposed from the other along 35 tion for contact of the adjacent electrodes attached there
an axis of geometrical revolution, a resilient means con
to, la closed-end epoxy resin tube encapsulating said plu
nected to each of said shells in such manner as to allow
relative movement therebetween along said axis of ge
rality of polarized piezoelectric discs, said epoxy resin
tube having a modulus .of elasticity that is smaller than
that of said discs, said epoxy resin tube being disposed
ometn'cal revolution, a plurality of polarized piezoelec
tric discs having silver electrodes attached to the faces 40 Within said pair of spatially disposed hemispherically
thereof, said discs being stacked along said axis of ge
shaped shell means. and connected thereto ‘at the closed
ometrical revolution for contact of the adjacent silver
ends thereof respectively, a toroidal transformer disposed
electrodes attached thereto, conductor means coupled to
around said epoxy resin tube Within said pair of spatially
said silver electrodes for eifectively connecting said piezo
disposed hemispherically shaped shell means, resilient
electric discs in electrical parallel, means encapsulating
means interconnecting said epoxy resin tube and said
said piezoelectric discs, silver electrodes, and conductors
toroidal transformer for supporting same in a predeter
for supporting same as an insulated unitary elongatalble
mined relative relationship, means interconnecting said
column, means connected between the ends of said col
torodial transformer and the aforesaid electrodes for sup
umn and the aforesaid hemispherical shells respectively
plying electrical power thereto, and a waterproof elec
for mounting same therein, a toroidal transformer sur
rounding said column, sponge rubber means interconnect
ing said column and said transformer for resiliently sup
porting same, means interconnecting said transformer
and the aforesaid silver electrodes for supplying electrical
excitation power thereto, and means connected to said
transformer adapted for supplying electrical excitation
power thereto from l3. source external of said hemispher
ical shells while same is insulatedly submerged within
said water.
8. The device of claim 7 further comprising a cement 60
disposed between said stacked discs.
9. The means of claim 7 wherein said pair of hollow
hemispherical shells each of which is spatially disposed
from the other along an axis ‘of geometrical revolution
consists of an aluminum metal,
65
trical coupling mounted on one of said pair of spatially
disposed hem-ispherically shaped shell means electrically
connected to said toroidal transformer and adapted for
being electrically coupled to an excitation and utilize,
tion means,
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,116,522
2,434,900
2,636,134
‘2,762,032
2,832,843
2,894,317
2,962,695
2,988,728
Kunze _______________ __ May 10,
Black et al _____________ __ Ian. 27,
Arons et al. __________ __ Apr. 21,
Vogel _________________ __ Sept. 4,
Miessner ____________ __ Apr. 29,
Marks ______________ __ July 14,
Harris __________ __i____ Nov. 29,
Marlow ______________ __ June 3,
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