Improvements in Telephone Transmitters.
Year: 1898

page_text: Improvements in Telephone Transmitters.
I, ALFRED GRAHAM, of 32, De Crespigny Park, Denmark Hill, in the County
of London, Electrical Engineer, do hereby declare the nature of this invention
to be as follows: -
This invention has for its object to construct a telephone transmitter in such
a manner that it can be used in an exposed position, as on a ship and other places,
or by a diver and otherwise in water, without liability of its efficiency being
impaired by leakage into it of moisture or water as would be the case with all
telephone transmitters heretofore constructed if used under the conditions
mentioned.
For this purpose the tension regulator of the transmitter is enclosed in a water-
tight case provided with a movable side or diaphragm adapted to transmit
vibrations of the external atmosphere to the tension regulator.
According to one construction the transmitter comprises a block or disc of
insulating material such as vulcanite which is plane on one side and formed at
the other with a central recess in which is placed a cup shaped disc of carbon
provided with an outer peripheral flange and adapted to hold carbon powder.
This carbon disc is in electrical connection with a metal ring by which it is held
in place in the recess by its flange and which is electrically connected to an external
plate of metal on the plane side of the insulating block or disc by screws, the
heads of which terminate within holes in the said plate. The outer ends of
these holes are sealed by material such as solder so as to obviate any liability of
moisture entering the case along the screws. To the insulating block or disc
is secured, as by screws, a metal ring preferably made as a cap piece of L section,
a layer of insulating adhesive material, for example shellac varnish, being pre-
ferably applied between the two to ensure a water tight joint between them, over
the open end of the carbon cup is placed a thin carbon disc or diaphragm that is
covered on its outer side with a disc of metal foil, such as copper foil, the two
discs being clamped at their periphery between the metal ring or cap piece
secured to or around the block of insulating material and a second metal ring
which is screwed to the first one by screws the heads of which terminate within
holes formed in the second ring and the outer ends of which are sealed as by
solder, for the purpose herein before mentioned. The outer peripheries of the
two rings and the inner periphery of the second ring and adjacent part of the
disc of metal foil are soldered together to ensure a water tight closure between
them. The interior of the case may be coated with a layer of waterproof material,
for example shellac varnish, for a like purpose.
To enable a telephone transmitter to successfully withstand shocks such as it
would be liable to receive on board a war ship, the carbon cup or receptacle used
for holding the carbon powder in place is seated upon cushioned material which
may conveniently consist of several discs of paper and one or more discs of cotton
lint, wool or felt, or metal springs or washers may be used. Also between the

page_text: edge of the carbon cup or receptacle and the carbon disc between which the
carbon powder is confined, there is preferably placed a ring of soft material such
as cotton lint, wool or felt the inner edge of which is caused to, bear against the
disc and prevent lateral escape of carbon powder.
I, ALFRED GRAILAM, of 32, De Crespigny Park, Denmark Hill, in the County
of London, Electrical Engineer, 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 has for its object to construct a telephone transmitter in such
a manner that it can be used in an exposed position, as on a ship and other places,
or by a diver and otherwise in water, without liability of its efficiency being
impaired by leakage into it of moisture or water as would be the case with all
other telephone transmitters, known to me, if used under the conditions mentioned.
For this purpose the tension regulator of the transmitter is enclosed in a water-
tight case provided with a movable side or diaphragm adapted to transmit
vibrations of the external atmosphere to the said tension regulator.
The accompanying drawing shows, in vertical section, one construction of
water-proof transmitter according to this invention.
According to this construction the transmitter comprises a circular block 1 of
insulating material such as vulcanized fibre, made plane at its rear side and with a
recess 1 in its front side in which is placed a carbon cup 2 which is moulded with
a flange 2 and is adapted to hold carbon powder 3. The carbon cup 2 is in
electrical connection with a metal ring 4 by which it is held in the recess 1" and
which is electrically connected to an external plate 5 of metal by screws 6 the
heads of which terminate, as shown, within holes in the said plate. The outer
ends of these holes are sealed by material 7 such as solder, so as to obviate any
liability of moisture entering the transmitter along the screws 6. To the block 1
is secured, as by screws 8, a metal ring 9, preferably made (as shown) as a
cap piece of L section, a layer of insulating adhesive material, for example shellac
varnish, being preferably applied between the two to ensure a water-tight joint
between them. Over the open end of the carbon cup 2 is placed a thin carbon
disc or diaphragm 10 which is covered on its outer side with a disc 10ª of metal
foil such as copper foil, the two discs being clamped at their periphery, between
the metal ring 9 and a second metal ring 11. This second ring 11 is secured to
the ring 9 by screws 12 the heads of which terminate within holes that are formed
in the ring 11 and the outer ends of which are sealed, as by solder 13, for the
purpose herein before mentioned. The outer peripheries of the two rings 9 and 11,
and the inner periphery of the second ring 11 and the adjacent part of the disc of
metal foil 10 are soldered together as shown at 14 and 14" respectively to insure
water tight joints between these parts at the places mentioned. The interior of
the transmitter case may, for a like purpose, be coated with a layer of water-
proof material, for example shellac varnish. The two discs or diaphragms 10, 10°
.

page_text: serve to transmit vibrations of the external atmosphere to the tension regulation,
the metal disc or diaphragm 10" also enabling a soldered and water-tight joint
to be made between it and the clamping ring 11.
To enable the telephone transmitter to successfully withstand shocks such as
it is liable to receive on board a war ship, the carbon cup 2 may be seated upon
cushioning material 15, which may conveniently consist of several layers of
paper and one or more layers of cotton, lint, wool or felt; or metal springs may
be used. Also between the edge of the carbon cup 2 and the carbon disc 10
there is preferably placed a ring 16 of soft material, such as cotton, lint, wool,
or felt that is held in place by a rigid ring 16 and the inner edge of which
ring 16 is caused to bear against the said disc 10 so as to prevent escape from th
carbon cup of the carbon powder 3. This carbon powder should only partly
fill the space between the carbon cup 2 and disc 10.
Around the waterproof transmitter thus constructed may be fixed a ring 17
formed with a flaring mouth piece 17. This ring and mouth piece may be of
insulating material or of metal. In the latter case it should be insulated from
the exterior of the transmitter by a ring 18 of suitable insulating material, for
example vulcanized fibre, of L section. Also, between the conical mouth piece 17"
and a conical distance piece 19 of insulating material, there may be clamped a
perforated or reticulated metal plate 20 for the purpose of protecting the carbon
and metal discs 10, 10" from injury.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what [
claim is:-
—
1. A telephone transmitter wherein the tension regulator is enclosed within a
water-tight case provided with a movable side or diaphragm adapted to transmit
vibrations of the external atmosphere to the said tension regulator as herein set
forth.
2. A telephone transmitter of the kind referred to in the preceding claim
wherein the tension regulator comprises a carbon cup seated upon cushioning
material consisting for example of layers of paper, or one or more layers of cotton,
lint, wool or felt, or metal springs, whereby it is enabled to withstand shocks, as
set forth.
3. A water-proof telephone transmitter constructed substantially as described
and shown.