Improvements in Telephone Transmitters.
Year: 1896

page_text: Date of Application, 7th Apr., 1896
Complete Specification Left, 29th Dec., 1896-Accepted, 30th Jan., 1897
PROVISIONAL SPECIFICATION.
Improvements in Telephone Transmitters.
We, WALTER LOUIS WILHELM, of 64 Norwood Avenue, Buffalo, New York,
Electrician, and BYRON JOHN TILLMAN, of 360 Fargo Avenue, Buffalo, New
York, Lawyer, both in the United States of America, do hereby declare the nature
of this invention to be as follows:-
This invention relates to that class of telephone microphones or transmitters which
contain two separate diaphragms bearing against opposite sides of the same electrode
and a single mouth piece from which the sound is delivered by two branch tubes
against both diaphragms.
The object of my invention is to produce a transmitter of this character which is
extremely simple and inexpensive in construction and which can be easily assembled
and adjusted.
The apparatus consists of a mouth piece and two branch tubes or passages
connected at their front ends with the rear end of the mouth piece. Two vertical
supporting disks are secured to the open rear ends of the branch tubes and arranged
parallel. The supporting disks are separated from each other along their entire
opposing surface thereby forming an open sided chamber or space between the
supporting disks into which the transmitting devices can be inserted from the side
for assembling the parts or to be removed therefrom for adjusting or repairing the
same. This transmitting device is constructed as follows:-
A rotary supporting ring or frame is held snugly between the supporting disks
by friction and is provided on opposite sides with annular shoulders or seats.
Two diaphragms are provided which are separated from the supporting disks by
intervening spaces and are fitted with their marginal portions against the seats of
the frame. These diaphragms may be made of any suitable and well known.
material which will answer the purpose but I prefer to make the same out of sheet
carbon. The electrode is arranged between the diaphragms and bears against the
central portions of both diaphragms. This electrode consists, preferably of a
granular material such as powdered carbon, or carbon dust although other granular
substance might work equally as well. The granular electrode is confined to the
central portion of the space between the diaphragms by a retaining ring which fills
the space between the electrode and the supporting frame. This retaining ring is
composed of any suitable fibrous material which is sufficiently dense to prevent the
powdered carbon from being displaced by creeping between the fibres thereof and
which is sufficiently elastic or yielding to permit the diaphragms to vibrate freely
for influencing the electrode. I have found in practice that cotton mineral wool
and eiderdown give excellent results.
Packing rings are arranged between the supporting disks and the marginal
portions of the diaphragms whereby the latter are held in place. The space
between the supporting disks is such that the transmitting device will be securely
held in position by friction after it is slipped between the supporting disks. The
vertical arrangement of the diaphragms causes the carbon dust electrode to be held
in contact with both diaphragms by gravity thereby always insuring a good
contact between these parts without requiring any special adjusting device for this
purpose.
When the carbon dust becomes packed or condensed in course of time by the
vibrations of the diaphragms, the carbon dust can be again loosened for restoring
it to its normal condition by rotating the transmitting device between the supporting

page_text: disks sufficiently to agitate and loosen the carbon dust, thereby preventing the
action of the transmitter from becoming impaired.
Two contact springs are arranged to form the terminals of the conducting wires
and are adapted to make connection with the carbon diaphragms when the transmitting
device is in its operative position.
Each of these contact springs is secured with one end by an insulated connection,
to the bottom of a pocket formed on the inner side of a supporting disk and bearing
with its curved free end against the adjacent diaphragms thereby forming a circuit
from one wire to the other through the diaphragms and the electrode. Upon
removing the transmitting device from between the disks, the springs slip off from
the diaphragms and recede into the pockets upon striking the packing ring and
frame whereby the circuit is broken and upon introducing the same again between
the disks, the springs again bear on the diaphragms and automatically restore the
circuit thereby enabling the working parts of the transmitter to be readily taken
apart and put together without requiring any attention to be paid to the connections
with the circuit wires.
The vibrations produced by speaking into the mouth piece are delivered by the
branch tubes against the outer sides of both diaphragms and the latter simultaneously
compress the granular electrode from opposite sides thereby increasing the force of
the undulations in the current which transmits the speech to the receiving
instrument in which the speech is reproduced.
In a modified construction of my invention a pair of transmitting devices similar
to that above described are employed and mounted as follows:-
The mouth piece is provided with two outer branch tubes aud an intermediate
tube. Two outer supporting disks are provided which are secured to the open rear
ends of the outer tubes. Two inner supporting disks are arranged on the inner
sides of the outer disks and secured to opposite sides of the open rear end of the
intermediate branch tube. A transmitting device, similar in every respect to the
one above described is inserted between each outer supporting disk and the opposing
inner supporting disk. The vibrations of the speech delivered into the mouth
piece are distributed equally between the intermediate tube which conducts the
sound to the inner diaphragms of both transmitting devices and the outer tubes,
whereby the sound is conducted to the outer diaphragms of both transmitting
devices.
Dated this 7th day of April 1896.
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.
impr ement
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We, WALTER LOUIS WILHELM, of 64 Norwood Avenue, Buffalo, New York,
Electrician, and BYRON JOHN TILLMAN, of 360 Fargo Avenue, Buffalo, New
York, Lawyer, both in the United States of America, do hereby declare the nature
of this invention and in what manner the same is to be performed to be particularly
described and ascertained in and by the following statement :-
This invention relates to that class of telephone microphones or transmitters
which contain two separate diaphragms bearing against opposite sides of the same
electrode and a single mouth piece from which the sound is delivered by two branch
tubes against both diaphragms.
The object of my invention is to produce a transmitter of this character which
is extremely simple and inexpensive in construction and which can be easily
assembled and adjusted.

page_text: Figure 1 is a sectional elevation of my improved transmitter taken on the
line 1-1, Figure 2.
Figure 2 is a horizontal section of the same on the line 2-2, Figure 1.
Figure 3 is a detached side elevation of the transmitting device.
Figure 4 is a horizontal section showing a modification of my improved
transmitter.
Like letters of reference refer to like parts in the several figures.
Referring to Figures 1, 2 and 3, A represents a mouth piece and a a two branch
tubes or passages connected at their front ends with the rear end of the mouth
piece. B B represent two vertical supporting disks secured to the open rear ends
of the branch tubes and arranged parallel. The supporting disks are separated
from each other along their entire opposing surface thereby forming an open sided
chamber or space between the supporting disks into which the transmitting devices
can be inserted from the side for assembling the parts or to be removed therefrom
for adjusting or repairing the same. This transmitting device is constructed as
follows:-
C represents a rotary supporting ring or frame which is held snugly between the
supporting disks by friction and which is provided on opposite sides with annular
shoulders or seats c c.
D D represent two diaphragms which are separated from the supporting disks
by intervening spaces and which are fitted with their marginal portions against the
seats of the frame. These diaphragms may be made of any suitable and well known
material which will answer the purpose but I prefer to make the same out of sheet
carbon. E represents the electrode arranged between the diaphragm and bearing
against the central portions of both diaphragms. This electrode consists, preferably
of a granular material such as powdered carbon or carbon dust although some other
granular substance might work equally as well. The granular electrode is confined
to the central portion of the space between the diaphragms by a retaining ring F
which fills the space between the electrode and the supporting frame. This
retaining ring is composed of any suitable fibrous material which is sufficiently
dense to prevent the powdered carbon from being displaced by creeping between
the fibres thereof and which is sufficiently elastic or yielding to permit the
diaphragms to vibrate freely for influencing the electrode. I have found in
practice that cotton mineral wool and eiderdown give excellent results.
G represents packing rings arranged between the supporting disks and the
marginal portions of the diaphragms whereby the latter are held in place. The
space between the supporting disks is such that the transmitting device will be
securely held in position by friction after it is slipped between the supporting disks.
The vertical arrangement of the diaphragms causes the carbon dust electrode to be
held in contact with both diaphragms by gravity thereby always insuring a
good contact between these parts without requiring any special adjusting device
for this purpose.
When the carbon dust becomes packed or condensed in course of time by the
vibrations of the diaphragms, the carbon dust can be again loosened for restoring
it to its normal condition by rotating the transmitting device between the supporting
disks sufficiently to agitate and loosen the carbon dust, thereby preventing the
action of the transmitter from becoming impaired.
H H represent two contact springs which form the terminals of the conducting
wires h h and which are adapted to make connection with the carbon diaphragms
when the transmitting device is in its operative position.
Each of these contact springs is secured with one end by an insulated connection,
to the bottom of a pocket ¹ formed on the inner side of a supporting disk and
bearing with its curved free end against the adjacent diaphragms thereby forming
a circuit from one wire to the other through the diaphragms and the electrode.
Upon removing the transmitting device from between the disks, the springs slip off
from the diaphragms and recede into the pockets upon striking the packing ring

page_text: and frame whereby the circuit is broken and upon introducing the same again
between the disks, the springs again bear on the diaphragms and automatically
restore the circuit thereby enabling the working parts of the transmitter to be
readily taken apart and put together without requiring any attention to be paid to
the connections with the circuit wires.
The vibrations produced by speaking into the mouth piece are delivered by the
branch tubes against the outer sides of both diaphragms and the latter simul-
taneously compress the granular electrode from opposite sides thereby increasing
the force of the undulations in the current which transmits the speech to the
receiving instrument in which the speech is reproduced.
In the modified construction of my invention represented in Figure 4, a pair of
transmitting devices similar to that shown in Figures 1 and 2 are employed and
.mounted as follows:-
I represents a mouth piece provided with two onter branch tubes jj and an
intermediate tube j. kk are two outer supporting disks which are secured to the
open rear ends of the outer tubes. L L represent two inner supporting disks
arranged on the inner sides of the outer disks and secured to opposite sides of the
-open rear end of the intermediate branch tube. A transmitting device, similar in
every respect to the oue shown in Figures 1 and 2, is inserted between each outer
supporting disk and the opposing inner supporting disk. The vibrations of the
speech delivered into the mouth piece are distributed equally between the
intermediate tube which conducts the sound to the inner diaphragms of both
transmitting devices and the outer tubes whereby the sound is conducted to the
outer diaphragms of both trausmitting devices:
Having now particularly described and ascertained the nature of our said inven-
tion and in what manner the same is to be performed, we declare that what we
claim is :-
1. The combination with the mouth piece provided with two branch tubes, of
two supporting disks secured to said tubes and separated from each other so as to
form an open sided space between the disks and a transmitting device arranged in
said space, substantially as set forth.
2. The combination with the mouth piece provided with two branch tubes, of
two supporting disks secured to the open ends of the tubes and separated from each
other so as to form an open sided space between the disks, a supporting frame or
ring arranged between said disks and provided on opposite sides with annular seats,
two diaphragms bearing with their marginal portions against said seats, packing
rings fitting against the marginal portions of the diaphragms and an electrode
arranged between said diaphragms, substantially as set forth.
3. The combination with the mouth piece provided with two branch tubes, of
two supporting disks secured to the open ends of the branch tubes and separated
so as to form an open sided space between the disks, a transmitting device arranged
between said disks and provided with two diaphragms arranged adjacent to said
disks, and contact springs secured to said disks and bearing against said diaphragms,
substantially as set forth.
4. The combination with the mouth piece provided with two branch tubes, of
two parallel supporting disks secured to the open ends of the branch tubes and
provided on their inner sides with pockets, of a transmitting device arranged
between said disks and provided with two diaphragms and contact springs secured
to the bottom of the pockets and bearing against the diaphragms, substantially as
set forth.
Dated this 29th day of December 1896
HASELTINE, LAKE & Co.,
45 Southampton Buildings, London, W.C., Agents for the Applicants.