March 20, 1934. A. S. RINGEL

March 20, 1934. A. S. RINGEL
March 20, 1934.
A. S. RINGEL
1,951,531
SOUND TRANSLATI NG DEVI CE
Filed Feb. 12, 1951
A TTORNEY.
Patented Mar. 2i), 1934
1,951,531
UNITED STATES PATENT ÓFFÍCE
1,951,531
SOUND-TRANSLÁTING DEVICE
Abraham Somer Ringel, lVlerchantville,~ N. J., as'
slgnor, by mesne assignments, to Radio Corpo
ration of America, New York, N, Y., a corpora
tion of Delaware
Application February v12, 1931, Serial No. 515,190
17 Claims. (Cl. 179-4155)
My invention relates to sound-translating de the space bounded by the diaphragm, includes'
vices, such as loudspeakers and microphones, and an element of the magnetic system such as a cen
it has particular relation to translating devices of tral pole piece arranged Vto extend entirely
the electrodynamic type.
through such space.
In all sound-translating devices of the electro
It` should be understood that the space bound
dynamic or moving coil type, with which I am ed by the inner surface of said diaphragm in
familiar, the magnetic system extends away from cludes such space as may be considered _to be
the cone and coil, thereby occupying considerable included within the diaphragmvwhen the latter is
space. Such devices, particularly loudspeakers regarded as a containeri or enclosing element per
1c intended for use in “midget” radio receivers, take se. Regarding a conical diaphragm in the man
up space that can be used to advantage for other ner in which it is usually employed, with the base
radio apparatus. Furthermore, in centralized or periphery portion extending frontally,v such
radio installations of the type wherein each loud space is that located within the confines of the
speaker is disposed in a small niche in the Wall conical diaphragm on the front face thereof.
iii of a room, it is highly important that the front More brieñy and more generally stated, the space
to-back dimension of the apparatus be as small as bounded by the inner surface of the diaphragm
possible, and that the moving parts thereof be may be regarded as the space within the conical
protected against damage.
610
diaphragm on the concave side thereof as dis
'
It is, accordingly, an object of my invention to tinguished from the convex side.
zo provide a sound-translating device that shall oc
The novel features that I consider character
cupy minimum space compatible with efficiency. istie of my invention are set forth with particu
Another object of my invention is to provide a larity in the appended claims. The invention it
sound-translating device wherein all moving parts self, however, both as to its organization and its
are adequately protected against damage.
method of operation, together with additional ob
Another object of my invention is to provide jects and advantages thereof, will best be under
a sound-translating device that may be mounted stood from the following description of certain
as a unit in a shallow depression in the wall of
specific embodiments, when read in connection
a room.
with the accompanying drawing, in which:
Another object of my invention is to provide a
30 loudspeaker that shall be substantially non-direc
tive.
An additional object of my invention is to pro
vide improved means for supplying a loudspeaker
with currents at audio frequencies.
à
'
Fig. 1 is a front view, in elevation, of a sound
translating device constructed according to my
invention.
l
Fig. 2 is a cross-sectional view of the same
device taken along a line corresponding to the line
II-II in Fig. 1,
A still further and more speciñc object of my
Fig. 3 is a front view, in elevation, of a sound'
translating device, of alternative type, also con
invention is to provide, in a device of the type de
scribed, centering means for the moving coil that structed according to my invention,
Fig. 4 is a cross-sectional view of the device
shall be easily accessible for adjustment.
The foregoing objects and others related there shown in Fig. 3 taken along a line corresponding
40 to I accomplish, in part, by disposing certain of
to the line IV-IV in that ligure,
`
95
Fig. 5 is a fragmentary View, partly in section,
the magnetic system elements of a sound-trans
lating device exteriorly of a substantially conical of a base plate of alternative type,
Fig. 6 is a View, partly sectional and partly
diaphragm, or a diaphragm having any other
desired shape, and by disposing the remainder of diagrammatic, of an alternativeV form of coil
the magnetic system elements substantially en support and centering device, and»
10o
Fig. '7 is an end view of the centering device
tirely within the space bounded by the dia
.
.
phragm. I, furthermore, utilize one of the said shown in Fig. 6.
magnetic system elements as a support for the
lThe apparatus illustrated in Figs. l and 2 of
large end of the diaphragm and provide the said the drawing includes a U-shape permanent mag
element with a plurality of openings whereby it net 1 having an opening 3 in the flat portion, 105
serves as an ornamental and protective grille and
as an acoustic ñlter.
In a preferred embodiment of my invention
hereinafter described, the remainder of the mag
connecting the legs 5 thereof, of sufñcient size
to accommodate a voice-coil '7 and a central pole
piece 9. The central pole piece extends rear
wardly from a base platei 11, of magneticl matei
netic system elements, which are entirely> within rial, to. which the legs of the U-shape magnet 110
2
1,951,531
are aiiixed by means of a plurality of screws 13
or equivalent devices.
The periphery of a substantially conical dia
phragm 15, or of a diaphragm of some other de
sired shape, or a mounting ring 17 of flexible
able to provide one or more openings 43 there
through to prevent the entrapped air from del-V
eteriously affecting the frequency characteristics
of the device.
Acoustic-loading means, such as
felt, wool, or the like, may also be disposed with»
in the openings, or interiorly of the chamber
soy
material afñxed to the said periphery, is clamped
Vbetween a plurality of diaphragm mounting rings defined by the cup-shape element.
Under certain circumstances, it is advantageous
-19 and 21. The mounting rings provide a sup
porting frame for the periphery of the diaphragm, to entirely surround the central pole piece 9
10 which frame is held firmly against or anchored to with means for diffusing the higher frequency 85
the inner surface of the base plate 11 by a plu-v sounds to prevent them from being radiated as
rality of bolts 23 or equivalent devices, whereby
' the diaphragm lies entirely within the legs of the
a beam.
The diffusing means may take the form .
of a separate conical element (not shown) sur-`
U-shape magnetic elementI and is protected rounding the central pole piece and the ñeld coil
15
thereby.
,
The voice coil 7 is carried by a cup-shape coilform 25 añâxed to the smaller end of the dia
phragm, the said form being centered with re
spect to the annular air-gap defined by the cen
20 tral pole piece and the opening in the U-shape
magnet by a centering device 27, such as a screw
(if one is used), the contour of the said ele 90
ment approximating the contour of the inner
surface' of the cone. The spacing between the
sound diffusing element and the inner surface
of the cone is difficult to predict accurately in
asmuch as the said spacing is, to afgreat extent, 95
dependent upon the diameter of the cone, the
or the like,«which projects through the bottom maximum amplitudey of movement thereof, the
of the coil-form into the end of the central pole size of the openingsV in the grille and upon other
piece.
-
' The-'magnetic system, constituted by the bas
plate 11, the U-shape element 1, and the central
so
pole piece 9 may, alternatively, be energized by a
ñeld coil 29, as shown in Fig. 4 of the drawing. thin material, however, gives rise to undesirable
It also lies within the scope of my invention magnetic saturation at the point of attachment
to utilize the base plate as a protective grille for of the central pole-piece. I, therefore, propose 105
the device, as is shown in Figs. 3 and 4 of the
to increase the thickness of an otherwise relative
drawing, wherein elementsA similar to those il
ly thin plate, substantially as shown in Fig. 5,- by
lustrated in Figs. 1 and 2 are similarly desig
the addition of .a protuberant portion 45.
In addition to improving the magnetic circuit
of the device the protuberant portion may be 110
V nated.
35 .
variable factors.
If it were possible to make the entire base plate 100
of relatively thin sheet- material the cost of the
device would, to some extent Abe lessened. Too
A -The essential difference between the device il
lustrated in Figs'. 3 and 4 and the modified device given such a configuration that it serves as an
shown in Fig. 1, lies in the substitution of a effective diffuser for high frequency ¿sounds while
larger cover plate 31, through which extend a offering low impedance to sounds at low fre
plurality of perforations 33, for the small base
quencies.
'
>Direct egress for low frequency sounds is pro 115
plate 11. The' perforations may be circular, as
shown, or they may be given any ornamental vided for by a plurality of small openings 47,
configuration desirable.
The cover plate, vwhich is also a part of the
magnetic» circuit, is provided With a plurality of
diametrically disposed ears 35 through each of
which extends a bolt 37 that cooperates with a
55
suspension lug 39 for the purpose of ñrmly
vclamping the device to the margin of Yan opening
in a wall orin an analogous position.
It is also feasible to dispense with the bolts
23 that hold the diaphragm clamping rings 19
and Ä21 against the rear surface of the base
plate. In such event it is convenient to increase
the diameter of the outer ring 19’ and to clamp
it-betweenashoulder 41 on the U-shape element
11v and the base-plate by means of the screws 13
that hold the base-plate Yand the U-shape ele
ment together.
extending through the protuberant portion,
While sounds at high frequencies which do not
pass readily through the small openings 47, are
caused to “detour”, so to speak, by the inner face 120
of the said portion to emerge, together with
sounds at lower frequencies, from a plurality of
larger openings 49 provided in the thinner part
of the plate. The high frequency sounds are
thereby prevented from being directed from the 125 k
diaphragm in a beam.
.
The openings 47 have relatively high acoustic
Yinertance with respect to sounds at high fre~
quencies but present relatively low impedance
to the passage of loW frequnecy sounds and 130
their presence does not adversely influence the
diaphragm at such frequencies. In effect, there
fore, the diffuser is a low-pass acoustic filter.
From the foregoing description it will be seen
Acoustic loading material may be inserted in
the openings 47 and 49, if desirable, as shown 135
phragm and that a portion thereof, such as the at 49h in openings 49 for example.
ed that the magnetic circuit surrounds the dia
pole piece 9, extends entirely through the space
The leads to the voice-coil in either of the
bounded by the inner surface of the diaphragm, alternative forms of my improved device may be
such space, as hereinbefore pointed out, being brought out from the rear thereof in any desired
that space bounded by the surfaces of the con manner. For example, it is feasible to connect 140
cave side of the diaphragm. This space is also one of the leads directly to the centering device
adapted to receive and to provide for an acoustic 27 and to connect the other to a metallic solder
loading means, as will hereinafter be described ing lug, or the like, carried upon the bottom of
in connection with Fig. 5.
the voice-coil form, from which a single flexible
Furthermore, I have found it desirable, where connection may extend to an insulated binding 145
complete protection of the diaphragm is essential post mounted upon the U-shape magnetic ele
'
‘
and economy is not an importantfactor, to utilize ment.
acup-shaped element entirely enclosing the dia
I prefer, however, to dispense entirely with
phragm,instead of the U-shape magnet shown. the bottom of 'the coil-form, through which‘the
When using the cup-.shape element it is desir centering device extends, and to utilize,- instead,
1,951,531
3?
a plurality of resilient metallic elements 51 and system extending entirely through the space
52 that also serve as intermediate means for con
bounded by the inner surface of said diaphragm,
necting the voice coil '7 to the output terminals
53 of an amplifier or the like, as shown in Fig. 6.
The metallic elements, which may be cor
rugated to give them the requisite amount of
compliance, are disposed at right angles to each
other and are separated by an insulating spacer
and Vhigh frequency sound-diverting means dis
posed within the space bounded by the inner
surface of said diaphragm and immediately adn
jacent to the axis thereof, whereby the projec
tion of a narrow beam of high frequency sounds
is substantially prevented.
4. In a sound-translating device, a substantially
conical diaphragm, a voice-coil form carried by
the smaller end of said'diaphragm, an element
of a magnetic circuit extending through the
space bounded by said diaphragm and into said
coil form and means exterior of said diaphragm
for centering said coil with respect to said ele»
ment, said centering means being directly con
nected with and carried by the end of said mag
netic circuit element which extends into said
voice coil form.
5. In a sound-translating device, a substantially C) C21
conical diaphragm, a voice-coil form carried by
the smaller end of said diaphragm, an element
of a magnetic circuit extending through the
space bounded by said diaphragm and into said
coil form and means exterior of said diaphragm
for centering said coil with respect to said ele
ment, said voice-coil form being cup shaped and
enclosing the end of said magnetic circuit ele»
ment extending into it, and said centering means
being carried by said end of the magnetic circuit
element and extending through the bottom of said
cup shaped coil form to cooperate therewith.
6. In a sound translating device, a substantially
conical diaphragm, an element of a magnetic
system extending entirely through the space 1"
bounded by the inner surface of said diaphragm,
and acoustic filtering means disposed within the
55. The ends of each of the elements are bent
over to embrace the coil-form 25 and they may
be aflixed thereto by cement or by other appro
priate means, such as riveting.
Each element has a central opening 57 slightly
larger in diameter than an insulating sleeve 59
which extends therethrough, to permit of lateral
movement of the assembly for centering, upon
loosening of a clamping bolt 61 threadedly con
nected to the end of the central pole piece. The
head of the clamping bolt is insulated from the
rearwardly disposed resilient element 51 adja
cent thereto by a Washer 63 of appropriate ma
terial such as micanite or the like.
One terminal of the voice-coil is connected to
the metallic element _52, which rests against and
is in conductive engagement with the pole piece
9, and the other terminal is >connected to the
metallic element 5l which is provided with a
30
soldering lug 65.
The leads 53, from the ampliiier (not shown)
are connected, respectively, to the pole piece 9,
or to any part of the magnetic circuit compo
nents, and to the soldering lug, thus obviating
the necessity for flexible connections to the voice~
coil.
It will be apparent from the foregoing descrip
tion of my improved sound-translating device
that it is extremely compact and that it is pecu
liarly adapted for use in situations where space
is at a premium and where protection of the
space bounded by the inner surface of said di--
aphragm and immediately adjacent to the axis
diaphragm against injury is essential. My im thereof, whereby the projection of a narrow beam
proved sound-translating device is also advan of high frequency sounds is substantially pre
tageous in that it radiates sound substantially vented.
non-directively by reason of the inclusion there
in oi elements constituting a low-pass acoustic
ñlter and a diffuser for sounds at high frequen
cies.
'7. In a sound translating device, a substantially
conical diaphragm, an element of a magnetic
system extending entirely «through the space _f
bounded by the inner surface of said diaphragm,
’I‘he elimination of flexible leads is also an and low pass acoustic filtering means disposed
important phase of my invention since such leads within the space bounded by the inner surface
of said diaphragm and immediately adjacent to
are very prone to break during use.
Although I have illustrated and described sev the axis thereof, whereby the projection of a
Li C)
eral specific embodiments of my invention, nu narrow beam of high frequency sounds is sub
merous modifications thereof will be apparent stantially prevented.
8. In a loudspeaker, a magnet member, a conical
to those skilled in the art to which it pertains.
My invention, therefore, is not to be restricted diaphragm disposed within the boundaries there
except insofar as is necessitated by the prior art of, and a plurally perforated plate of magnetically
permeable material covering the base oi the
or bythe spirit of the appended claims.
I claim as my invention:
diaphragm and being in contact with diametri
l. In a sound-translating device, a diaphragm cally opposite portions of said magnet member,
having a surface of revolution, a voice-coil form the perforations adjacent the center of said plate
affixed to said diaphragm, an element of a mag being materially smaller in diameter than the
netic system extending entirely through the space
bounded by said diaphragm and supporting means
for said voice-coil form carried by said element.
2. In a sound translating device, a substantially
conical diaphragm, an element of a magnetic
system extending entirely through the space
bounded by the inner surface of said diaphragm,
and high frequency sound impedance means dis
posed within the space bounded by the inner
surface of said diaphragm and immediately ad
jacent to the axis thereof, whereby the projec
perforations adjacent the periphery thereof,
whereby, when the loudspeaker is in operation,
the projection of a narrow beam of high frequency
sounds is substantially prevented.
9. The invention set forth in claim 8 character
ized in that acoustic loading material is disposed
in certain of the larger perforations remote from
the center of the plate.
10. The invention set forth in claim 8 char
acterized in that the center of the plate provided
with the smaller perforations is materially
'
tion of a narrow beam of high frequency sounds thicker than the periphery thereof.
11. In a sound translating device, the combina
3. In a sound translating device, a substantially tion with a conical diaphragm, of a protective
conical diaphragm, an element of a magnetic casing enclosing said diaphragm and comprising
is substantially prevented.
4
1,951,531
a base plate adapted to form closure means> for a
wall opening and a cup shape member secured
tothe base plate and enclosing the diaphragm
between it and the base plate, said cup shape
member having a central opening, a coil form
connected with the diaphragm located in said
opening, a central pole piece secured to the base
plate and extending through said opening and
within the coil form, and means secured to the
end of the pole piece adjacent the coil form for
adjusting the position of the coil form within the
opening, said means extending exteriorly of the
casing, whereby the coil form maybe adjusted
without dismantling the device.
f
l2. In a sound translating device, the combina
tion with a conical diaphragm, of a protective
casing enclosing said diaphragm and comprising
the central opening, wherebylthe coil form may
be adjusted, and an electro-magnetic field coil
surrounding the central pole piece and located
between the inner conical face of the diaphragm
and the base plate, whereby it is adapted to pass
’a >magnetic ilux through the base plate, the vcup
80'
shape magnet and the central pole piece.
15. In a sound translating device, the combi
nation of a base plate adapted to be mounted in
a wall opening and having openings providing a
grille, a cup shape magnet having an edge secured
to the base plate in a position to lie Within said
wall opening and adapted to form a closed pro
tective cover at the rear of the plate, said magnet
having a central opening spaced from the base
plate, a coil form in said opening, a central pole
piece extending from and secured to the base
a base plate adapted to form closure means for a plate, said pole piece having one end located With
wall opening and a cup shape member secured to in the coil form and said central opening, a frus
the base plate and enclosing the diaphragm be
tro-conical diaphragm flexibly secured along its
tween it and the base plate, said cup shape mem
ber having a central opening, a coil form con
nected with the diaphragm located in said open
base end to the base plate and at its opposite end
85
90
95
to one end of the coil form, and means extend-v
ing from said end of the pole pieceY exteriorly of
ing, a central pole piece secured to the base plate the central opening, whereby thecoil form may
N) U. and extending through said opening and within be adjusted, certain of rsaid openings adjacent the 100
the coil form, and means secured to the end of center- of said base plate being of relatively small
the pole piece adjacent the coil form for adjust~ size for the passage of low frequency sounds, and
ing the position of the coil form within the open certain others of said openings being of a larger
ing, said means extending exteriorly of the casing size for the passage of low and high frequency
30 whereby the coil `form may be adjusted Without sounds, thereby to provide a sound filter, and a 105
dismantling the device, said last named means Ventilating opening _in said cup shape magnet.
16. ln a sound translating device, the combi
being arranged to provide electrical circuit ter
minals and including two insulated, resilient, nation of a base plate adapted to be mounted in
metallic members secured to the coil form at a Wall opening and having openings providing a
spaced points, and said base plate having a plu " grille, a magnet having its legs secured to the base 110
rality of openings of different size, the smaller plate in a position to lie within said wall opening,
openings being more adjacent to the center of the said magnet having a central opening spaced from
the base plate, a coil form in said opening, a cen
plate, whereby an acoustic filter is provided.
trai pole piece extending from and `secured to the
13. In a sound translating device, the combina
tion of a base plate adapted to be mounted in a ‘oase plate, said pole piece having one end located 115
wall opening and having openings providing a within the coil form and said central opening,
grille, a magnet having its legs secured to the base a frustro-conical diaphragm flexibly secured
plate in a position to lie within said wall opening, along its base end to the base plate and at its
said magnet having a central opening spaced from opposite end to one end of the coil form, means
the base plate, a coil form in said opening, a extendingfrom said end of the pole piece exte 120
central pole piece extending from andsecured to riorly of the central opening, >whereby the coil
the base plate, said pole piece having one end form may be adjusted, said means being adapted
located Within the coil form and said central toresiliently connect the opposite end of the coil
opening, a frustro-conical diaphragm flexibly se form with the pole piece and including two resil
cured along its ‘case end to the base plate and at ient metallic elements adjustably secured to the 125
its opposite end to one end of the coil form, and adjacent end of the central pole piece and being
means extending from said end of the pole piece further secured to the coil form at spaced points,
exteriorly of the central opening, whereby the coil and means for insulating said elements whereby
they are adapted to provide electrical circuit ter
form may be adjusted.
Y
130
14. In a sound translating device, the combi
l'l. An electrical sound translating device in
nation of a base plate adapted to be mounted in
a wall opening and having openings providing a cluding in combination, a base plate of magnetic
grille, a cup shape magnet having an edge secured material, a conical diaphragm mounted on and
to the base plate in a position to lie Within said supported by said base plate, the base of said
wall opening and adapted to form a closed pro» diaphragm being adjacent vto said base plate, a
tective cover at the rear of the plate, said magnet magnetic core member mounted on the base plate
having a central opening spaced from the base and extending therefrom through the apex of the
plate, a con form in said opening, a central pole conical diaphragm, and a frame of magnetic ma
piece extending from and secured to the base terial surrounding the apex of said conical dia
plate, said pole piece having one end located phragm and detachably secured to the base plate 140
within the coil form and said central opening, a independently of the diaphragm, whereby said
frustro-conical diaphragm flexibly secured along frame may be removed from the base plate With
its base end to the base plate and at its opposite out interfering with the diaphragm.
minals.
,
i
,
end to one end of the coil form, means extend
ing from said end of the pole piece exteriorly of
75
ABRAHAM SOMER RINGEL. >
145
150
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