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Патент USA US2532743

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Dec. 5, 1950
R. R. STEVENS
MICROPHONE WITH OPPOSITE ELECTRODES BEING
OF‘ VARYING AND CONSTANT CURVATURE
Filed Oct. 31, 1947
35
2,532,741
v//////.
i
lNl/ENTOR
By
R. R. STEVENS
A T TOR/VEY
2,532,741
Patented Dec. 5, 1950
PATENT" OFFICE
2532,7411
MICROPHONE. WITH' OPPOSITE. ELEC-v
TRTODES, BEING. OF" VARYINGQ AND‘
CONSTANT"CURYATURE"
Ralplr. m". Stevens; . Ghathamg- N2 J1, assi'gnorz to;
Bellu'l‘elenhonerhabcratories;,Incorpprated,,New
YnrkaNnY‘g ,a.-_ corporation of New York
Applicatiomactober '31, 1943“,v Sélfiit-IKNO: 783E239‘; 83-:Claims. '(Cl. 1789-122‘)
1,
This 1‘ invention’ relates-1 to» telephone. transmit’
terse and“ more“ particularl3r~= to" carhonv» granule‘
type transmitter‘ units- especially suit‘ablefor use:
in hand telephones;
One general object of'this ‘invention is-‘tok-img
prove the operating- charact‘eris'tics -of-" telephone“ ’
transmitters of" the~vv carbon“ granule’ type; More
speci?cally; onerobject' of‘v this? invention" is to.
obtainsubstantiallyuniform‘ performancerof such‘
sti?eninglcorrugations'or'?utes I4 and: connected;
to the» peripheral; portion: r2; by " an. annular" cor;
rugated or: trough‘ portion l5? whichiis sufficiently
?exible: to allow: lbodilyi vibration. of i the: central
' part l3. The diaphragm, together withamois
turei-prootifmembrane. l6“ and aimultt-apertured
protectivezcoven'orl'screen I1; is. secured to;
frame by. a. clamping ‘band l8;
Mountedlhythe diaphragmaand .v-ibratilethere
transmittersv for "a wide’ variety-"ofvv positions in" 10,1. with? is an electrode IQ of 'para-boloid'all' form and‘
havingT a flange 281' and’ tabsv 2!‘ between which
which they'ma'y'beheld‘during‘use;
the' inner" edge- portion: of," the' diaphragm is
In" one-illustrative embodiment" of'thi‘s invent
gripped; Al'sosecured‘ between the ?ange and’
tlon, a transmitter-unit“of‘the-*typerand" general"
tabseare' the~=innerv portions of" a‘, metallic. spider‘
construction disclosediiir \Patenti 22042822 "grant
‘= 22' and'ani annular; ?exible closure member 23;
ed‘ June“ 2,- 1936‘ to ‘ Artli‘urx-Ff Bennett " and W11;
for example of silk. The arms" of the’ spider,
liam L. Tu?nell comprisesa'pair'o? coaxial'idi‘shed
electrodes? and“ associated’ elements" huun'diirgv a,
carbon" granule chamber; one of‘ the:v electrodes
being ?xed.’ and‘ the-other being-coupled“ to a
diaphragm" to vibrate therewith.
'
In" accordancewithv one' feature ‘.Of
inven
tion; the surface‘of' one-of the electrodes‘ is a.
surface‘ of‘revolution' the" generat'rix "of "which- is:
which serves-res alead in conductor tothe elec
trode--\ l9, extend-toand‘ contact an inner, annu
lar-?ange» 24’on'theioundation member or frame
20: The outer portion of the closure member 23 is
held between a pair of insulating'rings 25' and‘26
withirrthe cylindricaliiportion‘l‘ H 0f“the> founda
than having, a generatrix-of1v constant. curvature.
The‘ two surfaces’are coaxial” and "in- ‘j uxtaposition
and because of the di?erencejn' the con?‘gurae
tions, of these- surfaces the gap‘ therebetween
tion mem’o'er; the’ring 26"being seated upon‘ an
insulatingspacer 2-1’ which in- turn bears against
the spider arms:
A ?xed‘ electrode-is mounted‘ upon the ring‘
25' and comprises‘ an annular ?ange 28' seated‘
on'this ring, and’av central: domed part having“ a
hemispherical i‘ surface 29 in juxtaposition to- and‘
which the unitmaybeheldan-optimum or sub
?xed’ electrode is‘ provided with" an aperture 30
of" continuously -' varying curvature and‘v the" sur
face" of'v the other: electrode also is‘ one' of'revolu
varies continuously‘ so that for each position in ' ' coaxial with the paraboloidal electrode I91
stantially optimum current path between the
two>electrodesobtains ' Alsoibecause" of‘ the dif
ference, the spacing between the-two: electrodes‘
may be madez quite‘ small‘ whereby‘v improved
modulation is obtained.
'
The invention and the above-noted and. other:
features thereofwill'be- understood; more. clearly.
and‘ fully; from the following detailed description;
with: referenceto the accompanying drawing-in,
which‘?
Fig.‘ Us a side'view insectionofla transmitter;
unit'illustrative of‘one embodimentlof this ,inven'-~
tion;v and‘
'
Fig. 2 is a fragmentary sectional view illus
trating a modi?cation of the unit shown in Fig. 1.
Referring now to the drawing, the transmitter
unit illustrated in Fig. 1 comprises an annular,
The"
through‘ which a-' ?lling" of ‘ carbon granules“ 31"
is. introduced into the chamber bounded by; the
electrode. l9‘; closure 23-,1ringi25‘ and‘ surface‘ 29.
" A‘capor-cover-Mf'crimped over‘ the ?xed elec
troclev cl‘osesthe- aperture ‘ 3 0."
The" ?xed‘; electrode. and; rings. 25v and 26. are
securely-held‘ in position in pile-up relation and"
againstLthet'?‘ange' 24 by, an annular clamping
band 33‘. one“ edge of which bears against an
insulating? disc’ 34 seated‘ upon the electrode
?ange 28.‘.
I
_
It: will‘ be. noted‘ that‘ because of the - difference
in the forms of‘th'e juxtaposed‘ surfaces ofthe
45 two electrodes, the spacing between these sur—
faces is continuously changing; speci?cally, in
the construction illustrated, this spacing ?rst
increases, passes through a maximum, then de
creases in the direction toward the diaphragm.
metallic foundation member or frame l0 having
a cylindrical portion ll of reduced diameter and 50 The continuous change in curvature of the vibra
tile electrode surface, it has been found, sub
having also a plane face against which the annu
stantially minimizes variations in the perform
lar peripheral portion 12 of a diaphragm is
ance of the unit with changes in position in
seated. The diaphragm, which may be formed
which the unit is held during use thereof. That
in one piece of light weight metal, includes a
central frusto-conical part I3 provided with 65 is, the operating characteristics of the unit are
2,532,741
3
4
substantially independent of the position of the
posed, coaxial and dished in the same direction,
unit.
Furthermore, the difference in the con?gura
tions of the juxtaposed electrode surfaces allows
one of said portions having a constant curvature
and the other of said portions having a locus of
close spacing of these electrodes and conse
quently high modulation, without packing of the
5
continuously changing curvature, means for
vibrating one of said electrodes relatively to the
other thereof, means including said electrodes
carbon granules.
bounding a chamber of inner surface including
The exact con?guration of the paraboloidal
said portions and comminuted resistance-vary
surface of the electrode I9 is of some moment.
ing material in the chamber.
Speci?cally, the generatrix of the surface is of 10
4. A telephone transmitter comprising a ?rst
the form given by the equation X2=ky, where
electrode having a concave dished portion, a
X is the coordinate normal to the common axis
second electrode having a convex surface extend~
of the two electrodes, y is the coordinate parallel
ing toward and coaxial with said dished portion,
to this axis, and k is a constant. Values of 7c be
tween 0.0563 and 0.169 have been found satis
factory.
diaphragm means coupled to the second elec—
15 trode for vibrating it relatively to the first elec
trode, said surface and the concave face of said
portion being shaped in accordance with differ
ent geometrical formulae having di?erent points
The embodiment of this invention illustrated
in Fig. 2 is similar to that shown in Fig. 1 and
heretofore described. However, in the ‘embodi
ment shown in the former ?gure, the surface 20
face and said face varying continuously there
35 of the ?xed electrode‘is frusto-conical. One
slope which was found suitable for the generatrix
over in any phase of vibration of the second elec
trode, means including said surface and said
of this surface was of the order of 45 degrees
with reference to the common axis of the two
electrodes.
sistance-varying material in the chamber.
Although speci?c embodiments of the inven
tion have been shown and described, it will be
understood that they are but illustrative and ,
of origin to provide a spacing between said sur
face bounding a chamber and comminuted re
5. A telephone transmitter in accordance with
claim 4 wherein'said surface is paraboloidal and
said face is substantially hemispherical.
'6. A telephone transmitter in accordance with
that various modi?cations may be made therein
claim 5 wherein the generatrix of said surface is
without departing from the scope and spirit of 30 of the form X2- : ky, where y is the coordinate
this invention as de?ned in the appended claims.
parallel to the common axis of said face and sur
For example, although in the embodiments illus
face, .,X is the other coordinate and k is a con
trated the entire convex surface of the vibratile ~
stant between about 0.0563 and 0.169.
electrode is paraboloidal, a portion thereof ad
7. A telephone transmitter in accordance with
jacent the ?ange 20 may be cylindrical and the 35 claim 4 wherein said face is frusto-conical and
remainder paraboloidal.
‘
'
-
said surface is paraboloidal.
.
1
Reference is made of the application Serial
No. 783,324 ?led October 31, 1947, of Herbert W.
8. A- telephone transmitter comprising a pair
of electrodes bounded each by a surface includ
Bryant wherein a related invention is disclosed
ing a dished portion, the dished portions of the
and claimed.
40 two surfaces facing each other and dished in the
What is claimed is:
‘
same direction along a common axis of revolution
1. A telephone transmitter including a pair of
but of diiierently varying steepness with respect
electrodes having opposed surfaces bounding a
thereto wherefore the spacing between said por
chamber, comminuted resistance-varying ma
tions is a maximum over an intermediate zone
terial in the chamber and means for vibrating 45 between the portions and decreases therefrom
one of the electrodes relatively to the other, the
toward each electrode, means including said por
opposed electrodes being respectively convex and
tions bounding a chamber, comminuted resist
concave toward the other and shaped in accord
ance-varying material in the chamber and means
ance with different geometrical formulae having
for vibrating one of said electrodes.
different points of origin to provide a spacing 50
RALPH R. STEVENS.
between the opposed surfaces which varies con~
tinuously thereover in any phase of vibration of
REFERENCES CITED
the one electrode.
The following references are of record in the
2. A telephone transmitter comprising a ?xed
?le of this patent?
electrode having a plurality of surfaces of which 55
UNITED STATES PATENTS
one is a concave surface, a vibratile electrode
having a convex surface of continously. changing
Number
Name
Date
curvature in juxtaposition to said concave sur
face, means including said concave and convex
surfaces bounding a chamber, and comminuted
resistance varying material in said chamber.
3. A telephone transmitter comprising a pair
of electrodes having each a surface including a
dished portion the dished portions being juxta
2,014,427
2,042,822
2,191,992
2,225,488
2,302,278
Eaton ___________ __ Sept. 17,
Bennett __________ __ June 2,
McLarn __________ __ Feb. 27,
Stevens __________ __ Dec. 17,
Voorhoeve _______ __ Nov. 17,
1935
1936
1940
1940
1942
2,320,433.
Herckmans _______ __ June 1, 1943
2,429,988
Bryant ___________ __ Nov. 4, 1947
.
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